15. Waves

For a wave propagating in a medium, identify the property which is independent of others.

• Wavelength

• Velocity

• Frequency

• All these depend on each other

The angle between particle velocity and wave velocity in a transverse wave is

• 0

A wave along a string has the following equation (x in metre and t in second): y = 0.02sin (30t − 4.0x), the speed of the waves is

• 4.0 m s–1

• 30 m s–1

• 7.5 m s–1

•  10 m s–1

A transverse sinusoidal wave of amplitude A, wavelength l and frequency f is travelling on a stretched string. The

maximum speed of any point on the string is v/10, where v is the speed of propagation of the wave. If

a = 10^–3 m and v = 10 m s⁻¹, then f (in Hz) is given by

Which of the following statement is false for a stationary wave?

• Every particle has a fixed amplitude, which is different from the amplitude of its nearest particle.

• All particles cross their mean position at the same time.

• All particles are oscillating with same amplitude.

• There is no net transfer of energy across any plane.

Stationary wave is represented by y = Asin(100t)cos(0.01x),

where y and A are in mm, t in s, and x in m. The velocity of stationary wave is

• 1 m s−1

• Not derivable

The frequency of fundamental note in an organ pipe is 240 Hz. On blowing air, frequencies 720 Hz and 1200 Hz are heard. This indicates that the organ pipe is

• close at both ends.

• close at one end.

• open at both ends.

• having holes like flute.

Two closed pipes have the same fundamental frequency. One is filled with oxygen and the other with hydrogen at the same temperature. Ratio of their lengths, respectively, is

• 1 : 4

• 4 : 1

• 1 : 2

• 2 : 1

Two tuning fork having frequencies 460 Hz and 456 Hz are tuned together. The time interval between succes- sive maximum intensity will be

• 1/4 s

• 1/2 s

• 1 s

• 4 s

Two sources A and B are sounding notes of frequency 680 Hz. A listener moves from A to B with a constant velocity u. If the speed of sound is 340 m s⁻¹, what must be the value of u so that he hears 10 beats/sound?

• 2 m s−1

• 2.5 m s−1

• 3 m s−1

• 3.5 m s−1