Engineering Physics Multiple Choice Questions on “Superposition of Waves”.
1. Which is different from others by units?
a) Phase difference
b) Mechanical equivalent
c) Loudness of sound
d) Poisson’s ratio
Answer: d
Clarification: Of all the given quantities, Poisson’s ratio has no units.
2. The waves, in which the particles of the medium vibrate in a direction perpendicular to the direction of wave motion, is known as __________
a) Transverse waves
b) Longitudinal waves
c) Propagated waves
d) Magnetic waves
Answer: a
Clarification: In transverse waves, particles of the medium vibrate in a direction perpendicular of the wave
3. The waves produced by a motor boat sailing in water are __________
a) Transverse
b) Longitudinal
c) Longitudinal and transverse
d) Stationary
Answer: c
Clarification: Transverse waves are generated on the water surface. Inside water longitudinal waves longitudinal waves are produced due to vibrations of the rudder.
4. For a wave propagating in a medium, identify the property that is independent of the others.
a) Velocity
b) Wavelengths
c) Frequency
d) All these depend on each other
Answer: c
Clarification: Wave velocity=frequency×wavelength
Frequency remains unchanged while velocity and wavelength and interdependent.
5. A boat at anchor is rocked by waves, whose crests are 100m apart and velocity is 25m/s. The boat bounces up once in every __________
a) 2500s
b) 75s
c) 4s
d) 0.25s
Answer: c
Clarification: ʎ=100m, v=25m/s
T=ʎ/v=100/25=4s.
6. A transverse wave passes through a string with the equation
y=10sinπ(0.02x-2t)
Where x is in metres and t in seconds. What is the maximum velocity of the particles in wave motion?
a) 63m/s
b) 78m/s
c) 100m/s
d) 121m/s
Answer: a
Clarification: y=10sinπ(0.02x-2t)
u=dy/dt=-20πcosπ(0.02x-2t)
umax=20π=63m/s.
7. If equation of a sound wave is
y=0.0015sin(62.8x+314t)
Then its wavelength will be __________
a) 0.1unit
b) 0.2units
c) 0.3unit
d) 2unit
Answer: a
Clarification: y=0.0015sin(62.8x+314t)
y=asin(2π/ʎ x+2π/T t)
2π/ʎ=62.8
ʎ = (2×3.14)/62.8=0.1unit.
8. The plane wave is described by the equation
y=3cos(x/4-10t-π/2),
Where c is in meters and t in seconds. The maximum velocity of the particles of the medium due to this is?
a) 30m/s
b) 3π/2 m/s
c) 3/4 m/s
d) 40m/s
Answer: a
Clarification: y=3cos(x/4-10t-π/2)
u=dy/dt=30sin(x/4-10t-π/2)
umax=30m/s.
9. The equation of wave is given by
y=10sin(2πt/30+α)
If the displacement is 5cm at t=0, then the total phase at t=7.5s will be __________
a) π/3rad
b) π/2rad
c) 2π/5rad
d) 2π/3rad
Answer: d
Clarification: y=10sin(2πt/30+α)
At t=0, 5=10sinα or sin α=1/2
α=π/6
Total phase at t=7.5s,
φ=(2π×7.5)/300+π/6=π/2+π/6=2π/3.
10. If two sound waves having a phase difference of 60°, then they will have a path difference of __________
a) ʎ/6
b) ʎ/3
c) ʎ
d) 3ʎ
Answer: a
Clarification: ∆φ=60°=π/3
∆x=ʎ/2π×∆φ=ʎ/2π×π/3=ʎ/6.