JEE Main Physics - Wave Motion
Exam Duration: 60 Mins Total Questions : 30
IF frequency of tuning fork is 400Hz, find how far the sound travels when forks make 30 vibrations? Given velocity of sound in air is 320 m/s.
- (a)
32m
- (b)
30m
- (c)
24m
- (d)
34m
The velocity of sound in hydrogen is 1224m/s.Its velocity in mixture of hydrogen and oxygen containing 4 parts by volume of hydrogen 1 parts of oxygen is
- (a)
612m/s
- (b)
1224m/s
- (c)
2448m/s
- (d)
306m/s
For stationary wave, \(y=4sin({\pi\over15})cos(96\pi t)\) Find out the distance between a node and text antinodes.
- (a)
7.5cm
- (b)
15cm
- (c)
30cm
- (d)
22.5cm
In fundamental mode, time taken by wave to reach closed end of the air filled pipe is 0.01s.The fundamental frequency is
- (a)
25Hz
- (b)
12.5Hz
- (c)
20Hz
- (d)
15Hz
Three sound waves of equal amplitudes have frequencies (v-1), V, (v+1).They superpose to give beat.The number of beats produced per second will be
- (a)
4
- (b)
3
- (c)
2
- (d)
1
When two tuning forks 9fork 1 and fork 2) are sounded simultaneously, 4beat/s are heard.Now some tape is attached on the prong of the fork2.When the tuning forks are sounded again, 6 beat/s are heard.If the frequency of fork 1 is 200Hz, then what was the original frequency of fork 2?
- (a)
200Hz
- (b)
202Hz
- (c)
196Hz
- (d)
204Hz
Sound waves in air are always longitudinal, because:
- (a)
density of air is very small
- (b)
air is a mixture of several gases
- (c)
air does not have a modulus of rigidity
- (d)
of the inherent characteristics of sound waves in air
Which of the following expressions is that of a simple harmonic progressive wave?
- (a)
A sin ωt
- (b)
A sin ωt cos kx
- (c)
Asin (ωt - kx )
- (d)
A cos kx
A sound wave of wavelength 90 ern in glass is refracted into air. If the velocity of sound in glass is 5400 m/sec, the wavelength of the wave in air is:
- (a)
55 cm
- (b)
5.5 cm
- (c)
55 m
- (d)
5.5 m
The equation of a sound wave is y = 0.0015 sin (62.4x + 316t). Find the wavelength of this wave:
- (a)
0.2 unit
- (b)
0.1 unit
- (c)
0.3 unit
- (d)
cannot be calculated
A wave is represented by the equation:
y=7sin\(\left( 7\pi t-0.04x+\frac { \pi }{ 3 } \right) \)
Where, x is in metres and t in seconds. The speed of the wave is:
- (a)
(175π)m/s
- (b)
(49π)m/s
- (c)
(49/π)m/s
- (d)
(0.28π)m/s
A transverse wave is described by the equation y = Yo sin 2π\(\left( ft+\frac { x }{ \lambda } \right) \)The maximum particle velocity is equal to four times the wave velocity if:
- (a)
- (b)
- (c)
- (d)
Waves of displacement amplitude A and angular frequency ധ travel in air with the same velocity. Which of the following waves has the highest intensity?
- (a)
A = 10x 10-4 m, ω = 500 s-1
- (b)
A = 2x 10-4 m, ω = 2000 s-1
- (c)
A = 2x 10-4 m, ω = 115 s-1
- (d)
A = 20x 10-4 m, ω = 200 s-1
At what temperature the velocity of sound in a gas is thrice of its velocity at 0° C?
- (a)
2184° C
- (b)
2457° C
- (c)
2184 K
- (d)
819 K
If the amplitude of sound is doubled and the frequency reduced to one-fourth, the intensity of sound at the same point will be:
- (a)
increased by a factor of 2
- (b)
decreased by a factor of 2
- (c)
decreased by a factor of 4
- (d)
unchanged
With the propagation of a longitudinal wave through a material medium, the quantities transmitted in the direction of propagation are:
- (a)
energy, momentum and mass
- (b)
energy
- (c)
energy and mass
- (d)
energy and linear momentum
Decibel is the unit of:
- (a)
intensity of light
- (b)
X-ray radiation capacity
- (c)
sound loudness
- (d)
energy of radiation
A note has a frequency 128Hz. The frequency of a note two octaves higher than it is:
- (a)
256 Hz
- (b)
64 Hz
- (c)
32 Hz
- (d)
384 Hz
Which of the following equations represents a wave?
- (a)
y = a(ωt - kx)
- (b)
y = a sin ωt
- (c)
y = a cos kx
- (d)
y=a sin (at-bx+c)
The velocities of sound in an ideal gas at temperatures T1 and T2 K are found to be V1 and V2 respectively. If the root mean square speeds of the Game gas at the same temperatures T1, and T2 are v1, and v2 respectively, then:
- (a)
v2 =v1(V2/V1)
- (b)
v2 =v1(V1/V2)
- (c)
\({ v }_{ 2 }={ v }_{ 1 }\sqrt { { V }_{ 2 }/{ V }_{ 1 } } \)
- (d)
\({ v }_{ 2 }={ v }_{ 1 }\sqrt { { V }_{ 1 }/{ V }_{ 2 } } \)
A thin plane membrane separates hydrogen at 7° C from hydrogen at 47° C, both being at the same pressure. If a collimated sound beam travelling from the cooler gas makes an angle of incidence of 30° at the membrane, the angle of refraction is:
- (a)
\({ sin }^{ -1 }\sqrt { \frac { 7 }{ 32 } } \)
- (b)
\({ sin }^{ -1 }\sqrt { \frac {2 }{ 7 } } \)
- (c)
\({ sin }^{ -1 }\sqrt { \frac { 4 }{ 7 } } \)
- (d)
\({ sin }^{ -1 }\sqrt { \frac { 7 }{ 4 } } \)
A plane sound wave is travelling in a medium. With reference to a frame A, its equation is y=a cos(ωt-kx). With reference to a frame B, moving with a constant velocity v in the direction of propagation of the wave, equation of the wave will be:
- (a)
y=a cos[(ω+kv)t-kx]
- (b)
y=-a cos[(ω-kv)t-kx]
- (c)
y=a cos[(ω-kv)t-kx0]
- (d)
y=a cos[(ω+kv)t+kx]
A travelling wave is partly reflected and partly transmitted from a rigid boundary. Let ai , ar and at be the amplitudes of incident wave, reflected wave and transmitted wave and Ii , Ir and It be the corresponding intensities. Then, choose the correct alternative:
- (a)
\(\frac{I_i}{I_r}=(\frac{a_i}{a_r})^2\)
- (b)
\(\frac{I_i}{I_t}=(\frac{a_i}{a_t})^2\)
- (c)
\(\frac{I_r}{I_t}=(\frac{a_r}{a_t})^2\)
- (d)
all of these
A point source emits sound equally in all directions in a non-absorbing medium. Two points P and Q are at a distance of9 m and 25 m respectively from the source. The ratio of the amplitude of waves at P and Q is:
- (a)
\(\frac{3}{5}\)
- (b)
\(\frac{5}{3}\)
- (c)
\(\frac{9}{25}\)
- (d)
\(\frac{25}{9}\)
The speed of sound through oxygen at T K is v ms-1 As the temperature becomes 2T and oxygen gas dissociated into atomic oxygen, the speed of sound:
- (a)
remains the same
- (b)
becomes 2 v
- (c)
becomes √2v
- (d)
none of these
Light can travel in vacuum but not sound, because:
- (a)
speed of sound is very much slower than light
- (b)
light waves are electromagnetic in nature
- (c)
sound waves are electromagnetic in nature
- (d)
light waves are not electromagnetic in nature
A steel rod 100 em long is clamped at its mid-point. The fundamental frequency of longitudinal vibrations of the rod is given to be 2.53 kHz. What is the speed of sound in steel?
- (a)
5.06 km/s
- (b)
6.06 km/s
- (c)
7.06 km/s
- (d)
8.06 km/s
Two points are located at a distance of 10 m and 15 m from the source of oscillation. The period of oscillation is 0.05 see and the velocity of the wave is 300 m/sec. What is the phase difference between the oscillations of two points?
- (a)
π rad
- (b)
π/6 rad
- (c)
π/3 rad
- (d)
2π/3 rad
The equation of a wave travelling on a string is y=\(4 sin[\frac{\pi}{2}(8t-\frac{x}{8})]\), where x, y are in cm and t in second. The velocity of the wave is:
- (a)
64cm/s, in - X-direction
- (b)
32cm/s, in - X -direction
- (c)
32cm/s, in + X-direction
- (d)
64 cm/s, in + X -direction
A transverse sinusoidal wave move along a string in. the positive X -direction at a speed of 10 cm/s. The wavelength of the wave is 0.5 m and its amplitude is 10 cm. At a particular time t, the snap-shot of the wave is shown in the figure. The velocity of point P when its displacement is 5 cm, is:
- (a)
\(\frac{\sqrt{3}\pi}{50}\widehat { j } m/s\)
- (b)
\(-\frac{\sqrt{3}\pi}{50}\widehat { j } m/s\)
- (c)
\(\frac{\sqrt{3}\pi}{50}\widehat { i } m/s\)
- (d)
\(-\frac{\sqrt{3}\pi}{50}\widehat { i } m/s\)