Sastry CBSE

Electric Charges and Fields  Important Questions for CBSE Class 12 Physics Coulombs Law, Electrostatic Field and Electric Dipole

1.Electric Charge Charge is the property associated with matter due to which it produces and experiences electric and magnetic effect. Benjamin Franklin introduced two types of charges namely positive charge and negative charge based on frictional electricity produced by rubbing two unlike objects like amber and wood.

2.Conductors and Insulators Those substances which readily allow the passage of electricity through them are called conductors, e.g. metals, the earth and those substances which offer high resistance to the passage of electricity are called insulators, e.g. plastic rod and nylon.

3.Transference of electrons is the cause of frictional electricity.

4.Additivity of Charges Charges are scalars and they add up like real numbers. It means if a system consists of ncharges q₁, q₂,  … ,q_n, then total charge of the system will be q₁ +q₂ + … +q_n.

5.Conservation of Charge The total charge of an isolated system is always conserved, i.e. initial and final charge of the system will be same.

6.Quantisation of Charge Charge exists in discrete amount rather than continuous value and hence, quantised.
Mathematically, charge on an object, q=±ne
where, n is an integer and e is electronic charge. When any physical quantity exists in discrete packets rather than in continuous amount, the quantity is said to be quantised. Hence, charge is quantised.

7.Units of Charge
(i)SI unit coulomb (C)
(ii) CGS system

• electrostatic unit, esu of charge or stat-coulomb (stat-C)
• electromagnetic unit, emu of charge or ab-C (ab-coulomb)

1 ab-C = 10 C, 1 C = 3 x 10⁹ stat-C

8.Coulomb’s Law It states that the electrostatic force of interaction or repulsion acting between two stationary point charges is given by

9.Electrostatic forces (Coulombian forces) are conservative forces

10.Principle of Superposition of Electrostatic Forces This principle states that the net electric force experienced by a given charge particle q₀ due to a system of charged particles is equal to the vector sum of the forces exerted on it due to all the other charged particles of the system.

11.Electrostatic Force due to Continuous Charge Distribution
The region in which charges are closely spaced is said to have continuous distribution of charge. It is of three types given as below:

12.Electric Field Intensity The electric field intensity at any point due to source charge is defined as the force experienced per unit positive test charge placed at that point without disturbing the source charge.It is expressed as
Here, q₀ -> 0, i.e. the test charge q₀ must be small, so that it does not produce its own electric field.
SI unit of electric field intensity (E) is N/C and it is a vector quantity.

13.Electric Field Intensity (EFI) due to a Point Charge
Electric field intensity at P is, then

The magnitude of the electric field at a point P is given by

If q > 0, i.e. positive charge, then E is directed away from source charge. On the other hand if q < 0, i.e. negative charge, then E is directed towards the source charge.

14.Electric Field due to a System of Charges
Same as the case of electrostatic force, here we will apply principle of superposition, i.e.

15.Electric Field Lines Electric field lines are a way of pictorially mapping the electric field around a configuration of charge(s). These lines start on positive charge and end on negative charge. The tangent on these lines at any point gives the direction of field at that point.

16.Electric field lines due to positive and negative charge and their combinations are shown as below

17.Electric Dipole Two point charges of same magnitude and opposite nature separated by a small distance altogether form an electric dipole

18.Electric Dipole Moment The strength of an electric dipole is measured by a vector quantity known as electric dipole moment (p) which is the product of the charge (q) and separation between the charges (2l).

Direction Its direction is from negative charge (- q) to positive charge (+ q).
SI unit Its SI unit is C-m.
NOTE The line joining the two charges-q and + q is called the dipole axis.
(i)Electric Field at any Point on the Axial Line/End-on Position of Electric Dipole

The direction of electric field at any point on axial line is along the direction of electric dipole moment.
(ii) Electric Field at any Point on Equatorial Line/Broadside on  Position/Perpendicular Bisector of Electric Dipole

(ii)The direction of electric field intensity (E) due to dipole at any point on equatorial line is parallel to dipole and opposite to the direction of dipole moment.
If  l<<r,

19.Electric Field due to a Dipole Electric field of an electric dipole is the space around the dipole in which the electric effect of the dipole can be experienced.

21.Torque on an electric dipole placed in a uniform electric field (E) is given by

Previous Year Examination Questions

1 Mark Questions

1.Why do the electrostatic field lines not form closed loop?[All India 2014, Delhi 2012]
Ans.The electrostatic field lines do not form closed loop because no electric field lines exist inside the charged body

2.Why do the electric field lines never cross each other?[All India 2014]
Ans.At the intersection point, there would be two directions of electric field which is not possible so lines of forces never cross each other

3.Why must electrostatic field at the surface of a charge every point? Give reason. [Foreign 2014, Delhi 2012]
Ans.As, electric field inside a conductor is always zero. The electric lines of forces exert lateral pressure on each other leads to explain repulsion between like charges. Thus, in order to stable spacing, the         lines are normal to the surface.

4.Two point charges g_x and q₂ are placed at a distance d apart as shown in the figure. The electric field intensity is zero at the point P on the line joining them as shown. Write two conclusions that you can draw from this. [Delhi2014c]

Ans.(i) The two point charges (q^ and q₂) should be of opposite nature.
(ii) Magnitude of charge q₁ must be greater than magnitude of charge q₂.

5.Define dipole moment of an electric dipole. Is it a scalar quantity or a vector quantity?
[Foreign 2012; All India 2011]
Ans.Electric dipole moment of an electric dipole is equal to the product of its charges and the length of the electric dipole.It is denoted by p. Its unit is coulomb-metre.

It is a vector quantity and its direction is from negative charge towards positive charge

6.Draw a plot showing the variation of electric field (E) with distance r due to a point charge Q. [Delhi 2012]
Ans.The plot showing the variation of electric field and electric potential with distance r due to a point charge q is shown as below

7.A proton is placed in a uniform electric field directed along the position X-axis. In which direction will it tend to move? [Delhi 2011 c]
Ans.Proton will tend to move along the X-axis in the direction of a uniform electric field.

8. In which orientation, a dipole placed in a uniform electric field is in (i) stable (ii) unstable equilibrium?[Delhi 2011; All India 2008]
Ans.

9.Two point charges having equal charges separated by lm distance experience a force of 8 N. What will be the force experienced by them if they are held in water at the same distance? (Given, K_water = 80).[Ail India 2010 C]
Ans.Two point charges system is taken from air to water keeping other variable (e.g., distance, magnitude of charge) unchanged. So, only factor which may affect the interacting force is dielectric constant of medium

10.A metallic shpere is placed in a uniform electric field as shown in the figure. Which path is followed by electric field lines and why?[HOTS; Foreign 2010]

Ans.Path d is followed by electric field lines. Electric field intensity inside the metallic sphere will be zero, therefore, no electric lines of force exist inside the sphere, also lines fall normally on the surface. Electric field lines are always perpendicular to the surface of the conductor.

11.Point out right or wrong for the following statement.The mutual forces between two charges do not get affected by the presence of other charges.
Ans.Right, because mutual force acting between two point charges is proportional to the product of magnitude of charges and inversely proportional to the square of the distance between them, i.e. independent of the other charges.

12.A dipole of dipole moment p is present in a uniform electric field E . Write the value of the angle between p and E for which the torque experienced by the dipole, is minimum.       [Delhi 2009 c]
Ans.Since, torque (x) on the dipole in electric field E is

13.Two small identical dipoles AB and CD, each of dipole moment p are kept at an angle of 120° as

shown in the figure. What is the resultant dipole moment of this combination? If this system is subjected to electric field (E) directed along + X-direction, what will be the magnitude and direction of the torque acting on this? [Delhi 2008]

Ans.

2 Marks Questions

14.An electric dipole of length 4 cm when placed with its axis making an angle of 60° with a uniform electric field, experiences a torque of  . Calculate the potential energy of the dipole if it has charge ± 8 nC.[Delhi 2014]
Ans.

15.An electric dipole of length 2 cm when placed with its axis making an angle of 60° with a  uniform of  electric field,experiences a torque of   Calculate the potential energy of the dipole if it has charge of ± 4 nC.[Delhi 2014]
Ans.Refer to ans. 14 (Ans. 8J).

16.An electric dipole of length 1cm which placed with its axis making an angle of 60° with  a   uniform electric field,experiences a torque of  Calculate the potential energy of the dipole if it has charge ± 2 nC. [Delhi 2014]
Ans.Refer to ans. 14 (Ans. -6J).

17.Two point charges q and – 2 q are kept d distance apart, find the location of the point relative to charge to q at which potential due to this system is zero.[All India 2014]
Ans.

18.An electric dipole is placed in a uniform electric field E with its dipole moment p parallel to the field. Find
(i)the work done in turning the dipole till its dipole moment points in the direction opposite to E.
(ii)the orientation of the dipole for which the torque acting on it becomes maximum.[All India 2014 C]
Ans.

19.A small metal sphere carrying a charge +0 is located at the centre of a spherical cavity in a large uncharged metallic spherical shell. Write the charges on the inner and outer surfaces of the shell. Write the expression for the electric field at the point P_x. [Delhi 2014 c]

Ans.

20.(i) Point charge (+Q) is kept in the vicinity of and uncharged conducting plate. Sketch electric field lines between the charge and the plate.
(ii)Two infinitely large plane thin parallel sheets having surface charge densities  sigma1 and sigma2 (sigma1>sigma2) are shown in the figures. Write the magnitude and directions of net fields on the marked II and III. [Foreign 2014]

Ans.


In region II
The electric field due to the sheet of charge A will be from left of right (along the positive direction) and that due to the sheet of charge B will be from right to left (along the negative direction). Therefore, in region II we have

In region II
The electric fields due to both the charged sheets will be from left to right, i.e, along the positive direction. Therefore, in region III we have

21.Calculate the amount of work done in turning an electric dipole of dipole moment
from its position of unstable equilibrium to the position of stable equilibrium in a uniform electric field of intensity 10³ N/C. [Foreign 2011]
Ans.

Ans.

23.Two identical metallic spherical shells A and B having charges + 40 and -10Q are kept a certain distance apart. A third identical uncharged sphere C is first placed in contact with sphere A and then with sphere B, then spheres A and B are brought in contact and then separated. Find the charge on the spheres A and B.[All India 2011 c]
Ans.When two identical conducting charged spheres are brought in contact, then redistribution of charge takes place, i.e. the charge is equally divided on both the spheres.
When C and A are placed in contact, charge of A equally divides in two spheres. Therefore, charge on each A and C = + 2Q

24.A dipole with a dipole moment of magnitude p is in stable equilibrium in an electrostatic field of magnitude E. Find the work done in rotating this dipole to its position of unstable equilibrium.       [All India 2010c]
Ans.

25.A dipole is present in an electrostatic field of magnitude 10⁶N/C. If the work done in rotating it from its position of stable equilibrium to its position of unstable equilibrium is 2×10~23J, then find the magnitude of the dipole moment of this dipole.[All India 2010 C]
Ans.

26.Deduce the expression for the electric field E due to a system of two charges q_x and q₂ with position vectors i1 and r₂ at a point r with respect to common origin. [Delhi 2010c]
Ans.

27.The sum of two point charges is 7 microC. They repel each other with a force of 1 N when kept 30 cm apart in free space. Calculate the value of each charge.   [Foreign 2009]
Ans.

28.Figure shows two large metal plates and P₂ tightly held against each other and placed between two equal and unlike point charges perpendicular to the line joining them.
(i)What will happen to the plates when they are released?
(ii)Draw the pattern of the electric field lines for the system.[HOTS; Foreign 2009]

Ans.(i) By electrostatic induction, charge induces on the plates and opposite nature of charge appears on the surface facing each other. Therefore, they start attracting towards each other.

Field lines must be perpendicular to the plates. Also, equispaced field lines exist between two plates as electric field between, them is uniform.

29.Two charges + Q and -Q are kept at points (-x₂,0) and (x_t, 0) respectively, in the XY-plane. Find the magnitude and direction of the net electric field at the origin (0,0). [All India 2009 C]
Ans.

30.Two point charges 4Q and Q are separated by 1 m in air. At what point on the line joining of charges, is the electric field intensity zero? [All India 2008]
Ans.

3 Marks Questions

31.Two point charges + q and -2q are placed at the vertices B and C of an equilateral triangle ABC of side a as given in the figure. Obtain the expression for (i) the magnitude and (ii) the direction of the resultant electric field at the vertex A due to these two charges.

Ans.

32.Define the term electric dipole moment. Is it a scalar or vector? Deduce an expression for the electric field at a point on the equatorial plane of an electric dipole of length 2a.[All India 2013; Foreign 2009]
Ans.For electric dipole moment
Electric dipole moment of an electric dipole is equal to the product of its charges and the length of the electric dipole.It is denoted by p. Its unit is coulomb-metre.

It is a vector quantity and its direction is from negative charge towards positive charge
Consider an electric dipole AB consists of two charges +q and -q separated by a distance 2a. We have to find electric field at point P on equipotential line separated by a distance

33.Sketch the pattern of electric field lines due to
(i) a conducting sphere having negative charge on it.
(ii) an electric dipole.[All India 2011 C]
Ans.(i) Electric field lines due to a conducting sphere are shown in figure

(ii) Electric field lines due to an electric dipole are shown in figure

34.A positive point charge (+ q) is kept in the vicinity of an uncharged conduction plate. Sketch electric field lines originated from the point on to the surface Of the plate. [All India 2009; HOTS]
Ans.Equal charge of opposite nature induces in the surface of conductor nearer to the source charge

4 Marks Questions

35.Deduce the expression for the torque acting on a dipole of dipole moment p in the presence of a uniform electric field E.[All India 2014; Delhi 2008]
Ans.Torque on an Electric Dipole in a Uniform Electric Field Consider an electric dipole consisting of two charges – q and + q placed in a uniform external electric field of intensity The length of the electric dipole is 21.The dipole moment p makes an angle 0 with the direction of the electric field.
Two forces F and – F which are equal in magnitude and opposite in direction act on the dipole.

The net force is zero. Since, the two forces are equal in magnitude opposite in direction and act at different points, therefore, they constitute a couple.
A net torque x acts on the dipole about an axis passing through the mid-point of the dipole

36.While travelling back to his residence in the car, Dr. Pathak was caught up in a thunderstorm. It became very dark. He stopped driving the car and waited for thunderstorm to stop. Suddenly, he noticed a child walking alone on the road. He asked the boy to come inside the car till the thunderstorm stopped Dr.Pathak dropped the boy at his residence. The boy insisted that Dr. Pathak should meet his parents. The parents expressed their gratitude to Dr. Pathak for his concern for safety of the child.
Answer the following questions based on the above information
(i)Why is it safer to sit inside a car during a thunderstorm?
(ii)Which two values are displayed by Dr. Pathak in his action?
(iii)Which values are reflected in parents response to Dr. Pathak?
(iv)Give an example of similar action on your part in the past from everyday life.[Delhi 2013; VBQ]
Ans.(i)It is safer to be set inside a car during thunderstorm because the car acts like a Faraday cage. The metal in the car will shield you from any external electric fields and thus prevent the lightning from travelling within the car.
(ii) Awareness and humanity
(iii) Gratitude and obliged
(iv) I once came across to a situation where a puppy was stuck in the middle of a busy road during rain and was not able to go cross due to heavy flow, so I quickly rushed and helped him.

37.An electric dipole moment p is held in a uniform electric field E.
(i)Prove that no translation force acts on the dipole.
(ii)Hence, prove that the torque acting on the dipole is given by pE sin 0 indicating the direction along which it acts. [Foreign 2008]
Ans.(i)When dipole is placed in a  unifrom electric field, then force on +q charge due to electric field E

(ii)It is safer to be set inside a car during thunderstorm because the car acts like a Faraday cage. The metal in the car will shield you from any external electric fields and thus prevent the lightning from travelling within the car.
(a) Awareness and humanity
(b) Gratitude and obliged
(c) I once came across to a situation where a puppy was stuck in the middle of a busy road during rain and was not able to go cross due to heavy flow, so I quickly rushed and helped him.
Important Questions for Class 12 PhysicsClass 12 PhysicsNCERT Solutions Home Page

Alternating Current Important Questions for CBSE Class 12 Physics Introduction to Alternating Current

1.Alternating Current (AC) It is the current which varies in both magnitude as well as direction alternatively and periodically.

2.Effective Value or rms Value of AC It is defined as the value of AC over a complete cycle which would generate same amount of heat in a given resistors that is generated by steady current in the same resistor and in the same time during a complete cycle.

The 70.7% of peak value of current gives effective or rms value of AC

3. Average or Mean Value of AC It is defined as the value of AC which would send same amount of charge through a circuit in half-cycle that is sent by steady current in the same time.

The 63.7% of peak value of AC gives average or mean value of AC.

NOTE In a complete cycle of AC, the mean value of AC will be zero.

4. Alternating emf or Voltage It is the emf which varies in both magnitude as well as direction alternatively and periodically. The instantaneous alternating emf is given by

Previous Years’ Examination Questions

1 Mark Questions

1.Why is the use of AC voltage preferred over DC voltage? Give two reasons.    [All India 2014]

Ans. The use of AC voltage is preferred over DC voltage because of

(i) the loss of energy in transmitting the AC voltage over long distances with the help of step-up transformers is negligible as compared to DC voltage.

(ii) AC voltage can be stepped up and stepped down as per the requirement by using a transformer.

2.The current flowing through a pure inductance 2mH is, l =(15 cos 300t) A. What is the (i) rms and average value of current for a complete cycle? [Foreign 2011]

3. Define the term wattless current. [Delhi 2011]

4. Define the term rms value of the current. How is it related to the peak value?       [All India 2010c]

Ans.  It is defined as the value of Alternating Current (AC) over a complete cycle which would generate same amount of heat in a given resistor that is generated by steady current in the same resistor and in the same time during a complete cycle .lt is also called virtual value or effective value of AC.

5. How much average power over a complete cycle, does an AC source supply to a capacitor?    [Delhi 2009c]

Ans.  It is defined as the value of Alternating Current (AC) over a complete cycle which would generate same amount of heat in a given resistor that is generated by steady current in the same resistor and in the same time during a complete cycle .lt is also called virtual value or effective value of AC.

7. The instantaneous current and voltage of an AC circuit are given by I =(10 sin 300t) A and V= (200 sin 300t) V. What is the power dissipation in the circuit? [All India 2008]

8. The instantaneous current and voltage of an AC circuit are given by I = (10 sin 314t) A and V= (50 sin 314t) V. What is the power dissipation in the circuit? [All India 2008]

2 Marks Questions

10.A light bulb is rated 150 W for 220 V AC supply of 60 Hz. Calculate

• the resistance of the bulb
• the rms current through the bulb. [All India 2012]

11. Prove that an ideal capacitor in an AC circuit does not dissipate power. [Delhi 2011]

3 Marks Questions

13. (i) When an AC source is connected to an ideal capacitor, then show that the average power supplied by the source over a complete cycle is zero.

(ii) A lamp is connected in series with a capacitor. Predict your observations when the system is connected first across a DC and then  AC source. What happens in each case if the capacitance of the capacitor is reduced?            [Delhi 2013C]


Important Questions for Class 12 PhysicsClass 12 PhysicsNCERT Solutions Home Page

Human Reproduction  Important Questions for CBSE Class 12 Biology Reproductive Systems

1.Humans are sexually reproducing and viviparous organisms. There are remarkable differences between the reproductive events and systems in male and female.

2.Male reproductive system includes a pair of testes, accessory ducts, glands and the external genitalia.
(i)Testes are located outside the abdominal cavity within a pouch called Scrotum maintains the low temperature of the testes (2-2.5°C lower than the normal body temperature) required for spermatogenesis.
(a)Each testis is oval-shape (length 4-5 cm and width 2-3 cm) and covered by a dense covering called tunica albuginea.
(b)Internally it is divided into about 250 compartments known as testicular lobules.
(c)Each lobule contains 1-3 highly coiled (structural and functional units of testis) called seminiferous tubules in which sperms are produced.
(d)Seminiferous tubule is lined on its inside by two types of cells called male germ cells (spermatogonia) and Sertoli cells.
(e)Male germ cells undergo meiotic divisions finally leading to sperm formation.
(f)Sertoli cells provide nutrition to the germ cells.
(g)Interstitial spaces are present in outside regions of seminiferous tubules which contain small blood vessels and interstitial cells or Leydig cells.
(h)Leydig cells synthesise and secrete the testicular hormones called androgens
(ii)Male accessory ducts include rete testis, vasa efferentia, epididymis and vas deferens.
(a)The intratesticular duct system starts with tubuli recti, which are short, straight end segments of the seminiferous tubules. These tubules connect the seminiferous tubules to the highly anastomosing, cuboidal epithelium-lined channels called rete testis.
(b)From rete testis, 10-25 fine tubules arise called vasa efferentia that leave the testis and open into the epididymis.
(c)Epididymis leads to vas deferens that ascends to the abdomen and loops over the urinary bladder


Urinary bladder receives a duct from the seminal vesicle to form ejaculatory duct that runs through the prostate and opens into urethra.
(e) Urethra receives the ducts of prostate gland and the bulbourethral gland (Cowper’s glands) a little ahead and runs through the penis to its external opening called urethral meatus.
(iii) The accessory glands of male reproductive system include
(a)A pair of seminal vesicles, a prostate gland and a pair of bulbourethral glands (Cowper’s glands).
(b)The secretion of all these glands is called seminal plasma
(c)Seminal plasma contains fructose, calcium and some enzymes. It is to provide nutrition to the spermatozoa, while travelling through female reproductive tract.
(d)Seminal plasma along with sperms is called semen.
(e)Secretion of bulbourethral glands also helps in the lubrication of the penis.
(iv)External genitalia is the penis. It is made up of special erectile tissue that helps in erection of the penis. The enlarged tip of the penis is called glans penis. It is covered by a loose fold of skin called foreskin or prepuce.

3.Female reproductive system consists of a pair of ovaries, secondary sex organs, external genitalia and mammary glands.
(i)Ovaries are primary female sex organs which produce female gametes called ova and secrete the female sex hormones.
(a)These are located one on each side of the lower abdomen.
(b)It is almond-shaped, 2-4 cm in length, 1.5 cm in width.
(c)It is connected to the pelvic wall and uterus by ligaments.
(d)Each ovary is covered by a thin epithelium which encloses the ovarian stroma.
(e)Stroma is divided into two regions, i.e. peripheral cortex and inner medulla.
(ii)The female accessory ducts constitute oviducts (Fallopian tubes), uterus and vagina.
(iii)Each Fallopian tube is about 10-12 cm long and extends from the periphery of each ovary to the uterus.

(c)Infundibulum leads to a wider part of the oviduct called
(d)Isthmus is the last part of the oviduct, which has a narrow lumen and it joins the uterus.
(iv)Uterus or womb is a pear-shaped muscular organ. It is attached to the pelvic wall and supported by ligaments.
(a)Wall of the uterus has three layers of tissue.
(b)Perimetrium is the outermost thin membranous layer, myometrium is the middle thick layer of smooth muscles and endometrium is the innermost glandular layer which lines the uterine cavity.
(c)Uterus opens into the vagina through a narrow cervix, its cavity is called cervical canal, which along with vagina forms birth canal.
(d)Endometrium layer undergoes cyclic changes during menstrual cycle.
(e)Smooth muscles in myometrium contract during parturition to deliver the baby.
(v)Vagina is a muscular tube-like structure that opens to the outside. It receives spermatozoa during insemination and serve as birth canal.
(vi)Female external genitalia include mons pubis, labia majora, labia minora, clitoris and hymen.
(a)Mons pubis is a cushion of fatty tissue covered by skin and pubic hair.
(b)Labia majora are fleshy folds of tissue which extend down from the mons pubis and surround the vaginal opening.
(c)Labia minora are paired folds of tissue under the labia majora.
(d)Hymen is a membrane that covers the opening of vagina partially. It gets ruptured during vigorous physical activities or during the first coitus.
(e)Clitoris is a tiny finger-like structure, which lies at the upper junction of the two labia minora above the urethral opening.
(vii)Mammary glands (breasts) are paired structures that contain glandular tissue and variable amount of fat.
(a)Glandular tissue of each mammary gland is divided into 15-20 mammary lobes containing the cluster of cells called alveoli.
(b)The cells of alveoli secrete milk, which is stored in the cavities (lumen) of alveoli.
(c)Alveoli open into mammary tubules. The tubules of each lobe join to form a mammary duct.
(d)Several mammary ducts join to form a wider mammary ampulla, which is connected to lactiferous duct through which milk is sucked out.

Previous Year Examination Questions

1 Mark Questions

1.Why are humans testes located outside the abdominal cavity?Name the pouch in which they are present.    [All India 2014]
Ans.Human testes are located outside the abdominal cavity as it helps in maintaining low temperature, (2-2.5°C lower than body tempera­ture), required for spermatogenesis.Testes are enclosed in a pouch called scrotum.

2.Write the location and functions of following in human testes.
(i)Sertoli cells
(ii)Leydig cells [All India 2014]
Ans.(i) Location of Sertoli cells Within the lining of seminiferous tubule of testis.
Function of Sertoli cells They provide nutrition to the developing sperm cells.
(ii) Location of Leydig cells In the interstitial spaces between the seminiferous tubules.
Function of Leydig cells It synthesises and secrete hormones androgens, e.g. testosterone

3.List the different parts of human oviduct through which the ovum travels till it meets the sperm for fertilisation.[Delhi 2014 C]
Ans.The different parts of human female oviduct through which the ovum travels, till it gets fertilised are given below in the sequence.
(i) Fimbriae, finger-like projections Collect or catch the ovum, after ovulation.
(ii)Infundibulum Ovum from fimbriae is guided into funnel-shaped infundibulum, part of Fallopian tube.
(iii) Ampulla A wider part of oviduct that leads ovun into isthmus.
(iv) Isthmus With narrow lumen, and in the portion or junction of ampulla-isthmus, the ovum gets fertilised..

4.Write the location and function of Sertoli cells in humans.[Delhi 2012]
Ans.Location of Sertoli cells Within the lining of seminiferous tubule of testis.
Function of Sertoli cells They provide nutrition to the developing sperm cells.

2.Mark Questions

5.Where are fimbriae present in a human female reproductive system. Give their function.    [Delhi 2009]
Ans.Fimbriae are present in funnel-shaped edges of the Fallopian tube or oviduct in human female reproductive system. They help in the collection of ovum/secondary oocyte after ovulation.

6.Where are Leydig cells present? What is their role in reproduction? [All India 2009]
Ans.Location of Leydig cells In the interstitial spaces between the seminiferous tubules.
Function of Leydig cells It synthesises and secrete hormones androgens, e.g. testosterone

3 Marks Questions

7.Name and explain the role of inner and middle walls of human uterus. [Delhi 2014]
Ans.The innermost wall of uterus is  called endometrium.
Role of Endometrium
(i) It lines the uterine cavity and is glandular in nature
(ii)It undergoes cyclical changes during menstrual cycle.
The middle wall or layer of uterus is called myometrium.
Role of Myometrium
(i) It is made up of thick layer of smooth muscles.
(ii) It shows strong contractions during delivery of baby.

8.Draw a labelled diagrammatic view of human male reproductive system.[Delhi 2014]
Ans.Male reproductive system 
Male reproductive system includes a pair of testes, accessory ducts, glands and the external genitalia.
(i)Testes are located outside the abdominal cavity within a pouch called Scrotum maintains the low temperature of the testes (2-2.5°C lower than the normal body temperature) required for spermatogenesis.
(a)Each testis is oval-shape (length 4-5 cm and width 2-3 cm) and covered by a dense covering called tunica albuginea.
(b)Internally it is divided into about 250 compartments known as testicular lobules.
(c)Each lobule contains 1-3 highly coiled (structural and functional units of testis) called seminiferous tubules in which sperms are produced.
(d)Seminiferous tubule is lined on its inside by two types of cells called male germ cells (spermatogonia) and Sertoli cells.
(e)Male germ cells undergo meiotic divisions finally leading to sperm formation.
(f)Sertoli cells provide nutrition to the germ cells.
(g)Interstitial spaces are present in outside regions of seminiferous tubules which contain small blood vessels and interstitial cells or Leydig cells.
(h)Leydig cells synthesise and secrete the testicular hormones called androgens
(ii)Male accessory ducts include rete testis, vasa efferentia, epididymis and vas deferens.
(a)The intratesticular duct system starts with tubuli recti, which are short, straight end segments of the seminiferous tubules. These tubules connect the seminiferous tubules to the highly anastomosing, cuboidal epithelium-lined channels called rete testis.
(b)From rete testis, 10-25 fine tubules arise called vasa efferentia that leave the testis and open into the epididymis.
(c)Epididymis leads to vas deferens that ascends to the abdomen and loops over the urinary bladder


Urinary bladder receives a duct from the seminal vesicle to form ejaculatory duct that runs through the prostate and opens into urethra.
(e) Urethra receives the ducts of prostate gland and the bulbourethral gland (Cowper’s glands) a little ahead and runs through the penis to its external opening called urethral meatus.
(iii) The accessory glands of male reproductive system include
(a)A pair of seminal vesicles, a prostate gland and a pair of bulbourethral glands (Cowper’s glands).
(b)The secretion of all these glands is called seminal plasma
(c)Seminal plasma contains fructose, calcium and some enzymes. It is to provide nutrition to the spermatozoa, while travelling through female reproductive tract.
(d)Seminal plasma along with sperms is called semen.
(e)Secretion of bulbourethral glands also helps in the lubrication of the penis.
(iv)External genitalia is the penis. It is made up of special erectile tissue that helps in erection of the penis. The enlarged tip of the penis is called glans penis. It is covered by a loose fold of skin called foreskin or prepuce.

9.Draw a labelled diagram of the reproductive system in human female.[All India 2011]
Ans. Female reproductive system
Female reproductive system consists of a pair of ovaries, secondary sex organs, external genitalia and mammary glands.
(i)Ovaries are primary female sex organs which produce female gametes called ova and secrete the female sex hormones.
(a)These are located one on each side of the lower abdomen.
(b)It is almond-shaped, 2-4 cm in length, 1.5 cm in width.
(c)It is connected to the pelvic wall and uterus by ligaments.
(d)Each ovary is covered by a thin epithelium which encloses the ovarian stroma.
(e)Stroma is divided into two regions, i.e. peripheral cortex and inner medulla.
(ii)The female accessory ducts constitute oviducts (Fallopian tubes), uterus and vagina.
(iii)Each Fallopian tube is about 10-12 cm long and extends from the periphery of each ovary to the uterus.

(c)Infundibulum leads to a wider part of the oviduct called
(d)Isthmus is the last part of the oviduct, which has a narrow lumen and it joins the uterus.
(iv)Uterus or womb is a pear-shaped muscular organ. It is attached to the pelvic wall and supported by ligaments.
(a)Wall of the uterus has three layers of tissue.
(b)Perimetrium is the outermost thin membranous layer, myometrium is the middle thick layer of smooth muscles and endometrium is the innermost glandular layer which lines the uterine cavity.
(c)Uterus opens into the vagina through a narrow cervix, its cavity is called cervical canal, which along with vagina forms birth canal.
(d)Endometrium layer undergoes cyclic changes during menstrual cycle.
(e)Smooth muscles in myometrium contract during parturition to deliver the baby.
(v)Vagina is a muscular tube-like structure that opens to the outside. It receives spermatozoa during insemination and serve as birth canal.
(vi)Female external genitalia include mons pubis, labia majora, labia minora, clitoris and hymen.
(a)Mons pubis is a cushion of fatty tissue covered by skin and pubic hair.
(b)Labia majora are fleshy folds of tissue which extend down from the mons pubis and surround the vaginal opening.
(c)Labia minora are paired folds of tissue under the labia majora.
(d)Hymen is a membrane that covers the opening of vagina partially. It gets ruptured during vigorous physical activities or during the first coitus.
(e)Clitoris is a tiny finger-like structure, which lies at the upper junction of the two labia minora above the urethral opening.
(vii)Mammary glands (breasts) are paired structures that contain glandular tissue and variable amount of fat.
(a)Glandular tissue of each mammary gland is divided into 15-20 mammary lobes containing the cluster of cells called alveoli.
(b)The cells of alveoli secrete milk, which is stored in the cavities (lumen) of alveoli.
(c)Alveoli open into mammary tubules. The tubules of each lobe join to form a mammary duct.
(d)Several mammary ducts join to form a wider mammary ampulla, which is connected to lactiferous duct through which milk is sucked out.
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 Controlling Important Questions for CBSE Class 12 Business Studies Relationship between Planning and Controlling

1.Planning and controlling are two separate functions of management yet they are closely related and are called as inseparable twins of management.
2.Planning involves selecting enterprise’s objectives and deciding ways to achieve them. On the other hand, controlling is the process of assuring that actions are in line with plans.

Previous Year Examination Questions

4/5 Marks Questions

1.Explain the relationship between planning and controlling. (Compartment 2014)
or
‘Planning and controlling are inseparable twins of management’, how?(HOTS; Delhi 2013)
Ans. Planning and controlling are inseparable twins of management because:                                .
(i) Planning provides the basis for controlling activities.
(ii) Controlling ensures that planned goals are achieved efficiently and effectively. It measures
the performance with the pre-determined standards and finds out the deviations, if any.
(iii) The causes of deviations as remarked by controlling are the basis of effective future planning.
(iv) Planning and controlling both are forward looking as well as backward looking.
(v)Both are integral parts of an organisation and are necessary for the smooth functioning of an enterprise.

2.’There is a close and reciprocal relationship between planning and controlling’.
Explain this statement.  (hots; All India 2011; Delhi 2011)
Ans. Planning is the basis for control in the sense that it provides the entire spectrum on which control function is based. In fact, these two terms are often used together in the designation of the department which carries production, planning and scheduling. Control measures the behaviour and activities in the organisation and suggests measures to remove deviations, if any.
Control is the result of particular plans, goals or policies. Thus, planning offers and affects control. Also, planning is affected by control in the sense that many of the information provided by control is used for planning. Thus, there is a reciprocal relationship between planning and controlling.

6 Marks Questions

3.Describe the relationship between planning and controlling?
(All India 2014; Delhi 2014; Foreign 2014)
or
Explain controlling as a function of management. How are controlling and planning related? (All India 2011)
Ans. Controlling as a function of management can be defined as the process through which managers assure that the activities and results are in conformity with the planned activities and results. It involves verifying whether activities are performed according to the adopted plans.
Relationship between planning and controlling Planning involves selecting enterprise objectives and deciding ways to achieve them. Controlling is the process of assuring that actions are in line with the plans. Planning sets the course and control makes event to conform the chosen course or initiates action to appropriately change the plan. All controls imply existence of goals and plans. No manager can ascertain whether his subordinates are operating in the desired way unless he has a plan. Control will be much better, if the plans are clear and well coordinated.
Without planning, there is no basis for controlling activities. In the absence of plans, it is not possible to evaluate. In the absence of plans, it is not possible to evaluate performance. Similarly, without controlling, planned activities cannot be properly implemented and there cannot be improvement in future plans. Pre-determined goals can be achieved only through controlling. , Planning without control is useless and control without planning is meaningless. Planning, based on facts, makes controlling easier. Thus, planning and controlling are mutually inter-related and interdependent.

4.Rajeev and Sanjeev are managers in the same organisation heading different units. While discussing about the functions of management, Rajeev says that planning is looking ahead whereas, controlling is looking back. But Sanjeev says, ‘You are wrong because planning is looking back and controlling is looking ahead’.
Both are giving reasons in favour of their statements. Explain the possible reasons given by both and justify who is correct.   (hots; Delhi 2009 c)
or
Vipin and Jatin are managers in the same organisation heading different units. While discussing about the functions of management, Vipin says, ‘Planning is looking back whereas, controlling is looking ahead’. But Jatin says, ‘You are wrong because planning is looking ahead and controlling is looking back’.
Both are giving reason in favour of their statements. Explain the possible reason given by both and justify who is correct. (hots; ah India 2009)
Ans. Both the managers are correct, as planning and controlling both are backward looking as well as forward looking process.
Controlling is backward looking because it is like a postmortem of past activities. The manager looks back to previous years’ performance to find out its deviation from pre-determined standard. Planning is also backward looking because planning is guided by past experiences and feedback report of controlling function.
Planning is forward looking because plans are prepared for future. It involves looking in advance and making policy for maximum utilisation of resources in future.
Controlling is also forward looking because it does not end only by comparing past performance with standards. It involves finding the reasons for deviations and suggests the measures so that these deviations do not occur in future.
It can be stated that ‘planning is forward looking and controlling is backward looking’ is only partially correct as planning and controlling are both forward looking as well as backward looking process.

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Consumer Protection Important Questions for CBSE Class 12 Business Studies Role of Consumer Organisations and NGOs

1.Functions Performed by Consumer Organisations and NGOs
Following are the functions performed by consumer organisations and NGOs:
(i) Educating the public through organising training programmes, seminars and workshops.
(ii) Publish periodicals and other publications related to consumer rights, reliefs and other matter of interest.
(iii) Carrying out comparative testing of competitive products and publish results for consumer welfare.
(iv)Encouraging consumers to strongly protest and take action against unscrupulous, exploitative and unfair trade practices of sellers.
(v)Providing legal aid to consumers.
(vi)Filing complaints on behalf of consumers in the appropriate court.
(vii)Taking an initiative in filing a case in interest of general public, not for any individual.

2.Important Consumer Organisations and NGOs
Following are the important consumer organisations and NGOs
(i) Consumer Coordination Council, Delhi.
(ii) Common Cause, Delhi.
(iii) Voluntary Organisation in Interest of Consumer Education (VOICE), Delhi.
(iv)Consumer Education and Research Centre (CERC), Ahmedabad.
(v)Consumer Protection Council (CPC), Ahmedabad.
(vi)Consumer Guidance Society of India (CGSI), Mumbai.
(vii)Mumbai Grahak Panchayat, Mumbai.
(viii) Karnataka Consumer Service Society, Bangalore.
(ix)Consumers Association, Kolkata.
(x)Consumer Unity and Trust Society (CUTS), Jaipur.

Previous Year Examination Questions

1 Mark Question

1.Name any two Non-Governmental Organisations (NGOs) which are working in
India to protect and promote the consumer interests. (All India 2010)
Ans. (i) Consumer Guidance Society of India (CGSI), Mumbai.
(ii) Voluntary Organisation in Interest of Consumer Education (VOICE), Delhi.

 4/5 Marks Question

2.Explain any four functions of consumer organisation and Non-Government Organisations (NGOs ) for protecting and promoting the interest of consumers.(Delhi 2009)
Ans. Consumer organisations and NGO’s perform several functions for the protection and promotion of interest of consumers. These include
(i) Educating the general public about consumer rights by organising training programmes, seminars and work shops.
(ii) Publishing periodicals and other publications to impart knowledge about consumer problems, legal reporting, reliefs available and other matters of interest.
(iii) Carrying out comparative testing of products and publish results for consumer welfare.
(iv) Encouraging consumers to strongly protest and take an action against unscrupulous, exploitative and unfair trade practices of sellers.

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