MEDIUM
Earn 100

The intensity ratio of two waves is 1:9. The ratio of their amplitudes, is

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Important Questions on Waves

EASY

A uniform string of length 20 m is suspended from a rigid support. A short wave pulse is introduced at its lowest end. It starts moving up the string. The time taken to reach the support is 

(Take, g=10 m s-2)

MEDIUM
A hearing test is conducted on an aged person. It is found that her threshold of hearing is 20 dB at 1 kHz, and it rises linearly with frequency to, 60 dB at, 9 kHz. The minimum intensity of sound that the person can hear at, 5 kHz is,
MEDIUM
The intensity of sound during the festival season increased by, 100 times. This could imply a decibel level rise from-
MEDIUM
The pressure wave, P=0.01sin1000t-3xN m2 , corresponds to the sound produced by a vibrating blade on a day when atmospheric temperature is 0°C . On some other day when temperature is T , the speed of sound produced by the same blade and at the same frequency is found to be 336 m s1 . Approximate value of T is:
EASY
A travelling harmonic wave is represented by the equation yx, t=10-3sin50t+2x, where x and y are in meter and t is in seconds. Which of the following is a correct statement about the wave?
MEDIUM
A small speaker delivers 2 W of audio output. At what distance from the speaker will one detect 120  dB intensity sound? [Given reference intensity of sound as 10-12 W/m2 ]
HARD
A particle performing S.H.M. starts from the equilibrium position and its time period is 16 s. After 2 s its velocity is π m s-1. Amplitude of oscillation is cos45o=12
MEDIUM
For a transvers wave travelling, along a straight line, the distance between two peaks (crests) is 5 m, while the distance between one crest and one trough is 1.5 m. The possible wavelengths (in m) of the waves are:
MEDIUM
A string of length 1 m and mass 5 g is fixed at both ends. The tension in the string is 8.0 N. The string is set into vibration using an external vibrator of frequency 100 Hz. The separation between successive nodes on the string is close to
MEDIUM
A simple harmonic motion is represented by:
y=5sin3πt+3cos3πt cm
The amplitude and time period of the motion are:
EASY
Which characteristic of sound, makes it possible to recognize a person by his voice without seeing him?
EASY
Two waves of amplitudes A1 and A2 respectively are superimposed. The ratio between the maximum and minimum intensities of the resultant waves is 9:4. The value of A2 A1 is [Assume A1>A2]
EASY
A uniform thin rope of length 12 m and mass 6 kg hangs vertically from a rigid support and a block of mass 2 kg is attached to its free end. A transverse short wave train of wavelength 6 cm is produced at the lower and the rope. What is the wavelength of the wave train (in cm) when it reaches the top of the rope?
MEDIUM
A tunning fork of frequency 480 Hz is used in an experiment for measuring speed of sound v in air by resonance tube method. Resonance is observed to occur at two successive lengths of the air column, l1=30cm and l2=70  cm. Then, ν is equal to:
MEDIUM
When a particle of mass m is attached to a vertical spring of spring constant k and released, its motion, is described by yt=y0sin2ωt, where 'y' is measured from the lower end of upstretched spring. Then ω is :
EASY
Sound waves of wavelength λ and velocity v in medium- 1 enter medium- 2 . If their velocity in medium- 2 is 4 v, the wavelength in medium- 2 is
MEDIUM

A transverse wave propagating on a stretched string of linear density 3×10-4 kgm-1 is represented by the equation

y=0.2sin(1.5x+60t)

where, x in metres and t is in seconds. The tension in the string (in Newton) is

HARD
Two vectors A and B are defined as A=ai^ and B=acosωti^+sinωtj^, where a is a constant and ω=π6 rad s-1. If A+B=3A-B at time t=τ for the first time, the value of τ in seconds, is_______
MEDIUM
A uniform rope of length L and mass m1, hangs vertically from a rigid support. A block of mass m2 is attached to the free end of the rope. A transverse pulse of wavelength λ1 is produced at the lower end of the rope. The wavelength of the pulse when it reaches the top of the rope is λ2. The ratio λ2λ1 is:
HARD
The clocktower ("ghantaghar") of Dehradun is famous for the sound of its bell, which can be heard, albeit faintly, upto the outskirts of the city 8 km away. Let the intensity of this faint sound be 30 dB. The clock is situated 80 m high. The intensity at the base of the tower is:-