Find the wavelength, frequency and time period of the wave?

CBSE Class 9 CBSE Class 9 Science
1
  1. What is meant by frequency of sound waves?
  2. Give the range of frequencies of sound waves that an average human ear can detect.
  3. A source of wave produces 20 crests and 20 troughs in 0.2 s. The distance between a crest and next trough is 50 cm. Find the
    • wavelength
    • frequency
    • time period of the wave
2

1.Frequency The number of waves produced per second is called the frequency of the wave
2. 20 Hz to 20 kHz
3.

  • Since the distance between a crest and next trough is image
    Therefore, image = 50 cm
    ⇒ λ = 100 cm or 1 m
  • Distance covered in 20 crests = 20 x 1 = 20 m
    ∴ Velocity of the wave, v = vλ = image
    ⇒ image [∵ t = 0.2 s]
    ∴ v = 100 Hz
    or 1 crest and 1 through = 1 waves
    ∴ 20 crests and 20 throughs = 20 waves
    ∴ Frequency = image = image = 100 Hz
  • ∴ Time period, T = image = image = 0.01 s