8.1 Multiple choice questions
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1.
Wave is
a mechanism which transmits; |
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(a)
Wavelength |
(b)
Amplitude |
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(c)
Mass |
(d)
Energy |
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2.
The
wave which requires a medium for its propagation is known as: |
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(a)
Mechanical waves |
(b)
Electromagnetic waves |
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(c)
Radio waves |
(d)
Light waves |
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3.
Longitudinal
wave consists of |
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(a)
Crests and troughs |
(b)
Compression and rarefactions |
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(c)
Crests and compressions |
(d)
Troughs and rarefactions |
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4.
Transverse
wave is differ from longitudinal wave, because it possesses a property
of |
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(a)
Reflection |
(b)
Interference |
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(c)
Diffraction |
(d)
Polarization |
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5.
Due to
high elasticity, the speed of sound is maximum in |
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(a)
Solids |
(b)
Liquids |
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(c)
Gases |
(d)
Plasma |
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6.
The
speed of sound does not depend upon; |
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(a)
Density |
(b)
Elasticity |
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(c)
Temperature |
(d)
Pressure |
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7.
Which
of the following phenomenon is arisen by application superposition
principle |
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(a)
Interference |
(b)
Standing waves |
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(c)
Beats |
(d)
All of these |
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8.
When
two waves of same frequency and travelling in the same direction are
superimposed than we have |
|
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(a)
Interference |
(b)
Beats |
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(c)
Standing wave |
(d)
Stationary wave |
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9.
Which
one of the following changes can be observed in the resultant interference
wave? |
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|
(a)
Amplitude |
(b)
Time period |
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(c)
Wavelength |
(d)
Frequency |
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10. How many beats can be observed when the
difference in frequencies two waves is two;
|
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(a)
1 |
(b)
2 |
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(c)
3 |
(d)
4 |
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11. The length between node and antinodes is |
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(a) λ/4 |
(b) λ/2 |
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(c) λ |
(d) 2λ |
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12. Which one of the following waves does not
transmit energy? |
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(a)
Mechanical wave |
(b)
Standing wave |
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(c)
Matter wave |
(d)
Electromagnetic wave |
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13. The ratio of the fundamental frequency of an
open-ended pipe to a pipe whose One end is closed is; |
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(a)
1:1 |
(b)
1:2 |
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(c)
2:1 |
(d)
1:4 |
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14. Number of quantization frequency of
stationary wave in pipe when if one end is closed is; |
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(a)
The whole number |
(b)
Natural number |
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(c)
Even number |
(d)
Odd number |
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15. When wave is reflected from denser medium to
rare medium then there is phase change of; |
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(a) π/4 |
(b) π/2 |
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(c)
π |
(d)
2π |
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16. The sound which stimulates our ear is known
as |
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(a)
Sonic |
(b)
Infrasonic |
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(c)
Ultrasonic |
(d)
Tidal |
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17. Which one of the following parameters of a
wave does not change when it transmits through two different media |
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(a)
Amplitude |
(b)
Velocity |
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(c)
Frequency |
(d)
Wavelength |
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18. Doppler shift is occurred when; |
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(a)
Source in motion |
(b)
Observed |
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(c)
Source at rest |
(d)
Observer at rest |
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19. Piezoelectric effect means to produce the
electricity by; |
|
|
(a)
Thermal |
(b)
Mechanical |
|
(c)
Pressure |
(d)
Tidal |
Answers
- (d) Energy
- (a) Mechanical waves
- (b) Compression and rarefactions
- (d) Polarization
- (a) Solids
- (d) Pressure
- (d) All of these
- (a) Interference
- (a) Amplitude
- (b) 2
- (a) λ/4
- (b) Standing wave
- (c) 2:1
- (d) Odd number
- (c) π
- (a) Sonic
- (c) Frequency
- (a) Source in motion
- (c) Pressure
8.2 Short questions
6. What are the mathematical conditions of constructive and destructive
interferences?
7. By What factor would you have to multiply the tension in the string to
double the wave velocity?
8.3 Numerical problems
1. A pulse of a transverse wave
on a string moves at a distance of 15 m in 0.075 s (a) what is the velocity of
the pulse? (b) What is the frequency of a periodic wave on the same frequency?
If its wavelength is 0.8 m?
3. A steel wire 80 cm long has
mass of 8 g. If the wire is under a tension of 110 N. What is the speed of
transverse wave in the string?
5. An 80 m long stretched string
has a mass per unit length of 9 x 10-3 kg/m with tension of 20 N.
When the string is plucked, a stationary wave is setup in the string. Calculate
the fundamental frequency and the next three frequencies?
8. Two tuning forks A and B
produce 14 beats in 2 seconds. The frequency of the fork ‘A’ is 512 Hz. When a
little wax is attached to the prongs of the fork ‘B’ the beats disappear.
Determine the frequency of fork ‘B’.
10. Two cars P and Q are
travelling along a straight road in the same direction, the leading car P
travels at a steady speed of 12 ms-1. The other car Q travelling at
Steady speed of 20 ms-1
sound its horn to emit a steady note which P’s driver estimate has a frequency
of 830 Hz. What frequency does Q’s own driver hear? Speed of sound in air is
taken as 340 m/s
