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Multiple Choice Questions on Waves

Here you can see solved Multiple Choice Questions included in the course of First Year Physics.

(1) When a waves goes from one medium to another medium, which of the following characteristic of the wave remain constant.

(A) Volocity(B) Frequency(C) Wavelength(D)Phase
Explanation: Frequency of the wave is the same as the frequency of the source producing the wave. Obviously, the source is not part of the wave to enter from one medium to another. Therefore, it does not change when the wave enters from one medium into the other.

2. When a transverse wave is reflected from the boundary of a denser medium to a rare medium, it undergoes a phase change of:
(A) 0(B) π/2(C) π(D) 2π
(3) If the tension in the string is doubled and its mass per unit length is reduced to half, the speed of transverse wave on it is:
(A) doubled(B) halved(C) constant(D) one-fourth

Solution: The relation among the tension in the string, the mass per unit length of the string and velocity of the wave produced is given by 

Now if tension is doubled, T = 2T and mass per unit length is halved, m = m/2. Put these values in the above equation.

(4) Which one of the following properties is not exhibited by the longitudinal waves?
(A) reflection(B) interference(C) diffraction(D) polarization
See comprehensive question 9, chapter 9.
(5) A sounding source and a listener are both at rest relative to each other. If wind blows from the listener towards the source, then which one of the following of sound will change? ,/tr>
(A) Frequency(B)SpeedPhaseWavelength

(6) Which one of the following has no effect on the speed of sound in a gas?

(A) Humidity(B) Pressure(C) Temperature(D) Density

EXPLANATION: See question 6 in comprehensive questions.

(7) There is no net transfer of energy by particles of medium in,
(A) Longitudinal waves(B) Transverse waves(C) Progressive waves(D) Stationary waves

EXPLANATION: Energy cannot be transferred in case of stationary waves because at the node point, the particles of the medium are stationary. The standing (stationary) medium particle does not transfer the wave energy to the next particle of the medium.

(8) Which one of the following could be the frequency of ultraviolet radiation,
(A) 1.0× 106 Hz(B) 1.0 × 109 (C) 1.0 × 10121.0 × 1015
EXPLANATION: UV radiations are electromagnetic radiations. They fall in the frequency range of 8 × 1014 Hz to 3 × 1016 Hz.
(9) When a stationary wave is formed then its frequency is (A) same as that of the individual waves. (B) twice that of the individual waves. (C) half that of the individual waves. (D) &sqrt;2 that of the individual waves.
(10) The fundamental frequency of a closed organ pipe is f. If both ends are open then its fundamental frequency will be,
(A) f(B) 0.5f(C) 2f(D) 4f

Solution: For the closed pipe,

Similarly, v = fλ ⇒ f = v/λ. Put in the above equation,

And for open pipe,

So f’ = v/λ’ now implies,

(11)If the amplitude of a wave is doubled, then its intensity is,

(A) Doubled(B) Halved(C) Quadrupled(D) One-fourth

Explanation: Intensity of a wave is proportional to the amplitude of the wave. So when the amplitude doubles, intensity is quadrupled (i-e, becomes 4 times).
12. A sound source is moving towards a stationary listener with 1/10 of the speed of the sound. The ratio of apparent to real frequency is:

(A) 11/10(B) (11/10)2(C) (9/10)2(D) 10/9

Solution: The apparent frequency is given by the relation,

[See question 9 (1).]

The ratio of frequencies is, therefore, 

(From the above equation)

Put the values

 

 

 

 

 

 

 

See list of bookshops in Mardan, Takht Bhai, Katlang and Shergadh where you can have Mashal Physics 11, Or text on 03339986608 to have one at home.

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7 Comments

  1. danyal
    Reply

    We know that waves carry energy so after interference what happens to their energy in both constructive as well as destructive interference
    Also in stationary waves what happens to the energy possessed by the waves

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