CBSE Class 9 Physics Help

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  1. Vinila Choudary

    If 20 waves are produced per second, what is the frequency in hertz?

    Vinila Choudary, Jan 30, 2012
    Replies:
    1
    Views:
    1,950
    usama
    Nov 25, 2018
  2. Vinila Choudary

    when the train is far off but its sound cannot be heard through air. Why

    Vinila Choudary, Mar 23, 2012
    Replies:
    0
    Views:
    2,475
    Vinila Choudary
    Mar 23, 2012
  3. Vinila Choudary

    A powerful sound signal sent from a ship is received again after 2.4 seconds.

    Vinila Choudary, Mar 23, 2012
    Replies:
    0
    Views:
    746
    Vinila Choudary
    Mar 23, 2012
  4. Vinila Choudary

    The boy hears the echo of his shout after 4.8 seconds. Find the speed of the sound.

    Vinila Choudary, Mar 23, 2012
    Replies:
    0
    Views:
    644
    Vinila Choudary
    Mar 23, 2012
  5. Vinila Choudary

    A sound wave has a frequency 2 kHz and wavelength 40 cm. How long will it take to travel 1.6 km?

    Vinila Choudary, Mar 23, 2012
    Replies:
    0
    Views:
    1,039
    Vinila Choudary
    Mar 23, 2012
  6. Vinila Choudary

    calculate the distance of hill from the boy.

    Vinila Choudary, Mar 23, 2012
    Replies:
    0
    Views:
    637
    Vinila Choudary
    Mar 23, 2012
  7. Vinila Choudary

    calculate the wavelength and frequency of new wave.

    Vinila Choudary, Mar 23, 2012
    Replies:
    0
    Views:
    826
    Vinila Choudary
    Mar 23, 2012
  8. Vinila Choudary

    A longitudinal wave of wavelength 1 cm travels in air with a speed of 330 rn/s.

    Vinila Choudary, Mar 23, 2012
    Replies:
    0
    Views:
    643
    Vinila Choudary
    Mar 23, 2012
  9. Vinila Choudary

    The wavelength of waves produced on the surface of water is 20 cm.

    Vinila Choudary, Mar 23, 2012
    Replies:
    0
    Views:
    677
    Vinila Choudary
    Mar 23, 2012
  10. Vinila Choudary

    wavelength when frequency is 256 Hz.

    Vinila Choudary, Mar 23, 2012
    Replies:
    0
    Views:
    808
    Vinila Choudary
    Mar 23, 2012
  11. Vinila Choudary

    State the laws of reflection of sound.

    Vinila Choudary, Mar 23, 2012
    Replies:
    0
    Views:
    666
    Vinila Choudary
    Mar 23, 2012
  12. Vinila Choudary

    Describe an activity to study the reflection of sound.

    Vinila Choudary, Mar 23, 2012
    Replies:
    0
    Views:
    2,245
    Vinila Choudary
    Mar 23, 2012
  13. Vinila Choudary

    What is meant by reflection of sound?

    Vinila Choudary, Mar 23, 2012
    Replies:
    0
    Views:
    630
    Vinila Choudary
    Mar 23, 2012
  14. Vinila Choudary

    Why do we hear the sound produced by the humming bees

    Vinila Choudary, Feb 29, 2012
    Replies:
    0
    Views:
    867
    Vinila Choudary
    Feb 29, 2012
  15. Vinila Choudary

    What is a sound board? Explain the working of a soundboard with the help of a labelled diagram.

    Vinila Choudary, Feb 29, 2012
    Replies:
    0
    Views:
    1,924
    Vinila Choudary
    Feb 29, 2012
  16. Vinila Choudary

    Write any three applications of ultrasound.

    Vinila Choudary, Feb 29, 2012
    Replies:
    0
    Views:
    2,841
    Vinila Choudary
    Feb 29, 2012
  17. Vinila Choudary

    What do you mean by an echo? State two conditions for hearing a distinct echo.

    Vinila Choudary, Feb 29, 2012
    Replies:
    0
    Views:
    5,222
    Vinila Choudary
    Feb 29, 2012
  18. Vinila Choudary

    Explain the terms crests and troughs of a wave.

    Vinila Choudary, Feb 29, 2012
    Replies:
    0
    Views:
    855
    Vinila Choudary
    Feb 29, 2012
  19. Vinila Choudary

    What is a stethoscope? Name the principle on which a stethoscope works.

    Vinila Choudary, Feb 29, 2012
    Replies:
    0
    Views:
    5,957
    Vinila Choudary
    Feb 29, 2012
  20. Vinila Choudary

    What are transverse waves? Give two examples.

    Vinila Choudary, Feb 29, 2012
    Replies:
    0
    Views:
    768
    Vinila Choudary
    Feb 29, 2012
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