Multiple Choice QuestionsTwo closed organ pipes of length 100 cm and 101 cm produces 16 beats in 20 sec. When each pipe is sounded in its fundamental mode. Calculate the velocity of sound.
303 ms-1
332 ms-1
323.2 ms-1
300 ms-1yes
A siren emitting sound of frequency 800 Hz is going away from a static listener with a speed of 30 m/s. The frequency of sound heard by listener is ( velocity of sound = 300 m/s )
727.3 Hz
481.2 Hz
644.8 Hz
286.5 Hz
Assertion: Sound waves cannot travel in vacuum but light can travel in vacuum.
Reason: Sound waves are longitudinal waves and they cannot be polarised but electromagnetic waves are transverse and they can be polarised.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
B.
If both assertion and reason are true but reason is not the correct explanation of assertion
Light is an electromagnetic wave and sound is a longitudinal and mechanical wave. In vacuum nothing is present. Sound needs either solid, liquid or gas to propagate and hence it is called a mechanical wave. Sound wave is form of energy which is transferred by vibrating air molecules if motion of propagation is air. Air molecules themselves are not energy. But light is composed of photons and photons are energy themselves. Photons can travel in any medium. Light is produced if there is any change in electric and magnetic field but sound is produced by vibrating body.
In short light itself travels from one point to another and hence do not need any medium but sound is transferred by vibrating bodies and hence need a medium to travel.
For example:- A ringing bell placed in a jar and air inside the jar is evacuated. Once air is removed from the jar, the sound of the ringing bell can no longer be heard. The clapper is seen striking the bell; but the sound that it produces cannot be heard because there are no particles inside of the jar to transport the disturbance through the vacuum.
Both the assertion and reason are correct but reason is not the correct explanation for the assertion.
A stone thrown into still water, creates a circular wave pattern moving radially outwards. Ifr is the distance measured from the centre of the pattern, the amplitude of the wave varies as
r1/2
r-1
r2
r3/2
Which of the following diagrams represents the variation of electric field vector with time for a circularly polarized light?
When a guitar string is sounded with a 440 Hz tuning fork, a beat frequency of 5 Hz is heard. If the experiment is repeated with a tuning fork of 437 Hz, the beat frequency is 8 Hz. The string frequency (Hz) is
445
435
429
448
For a wave propagating in a medium, identify the property that is independent of the others.
Velocity
Wavelength
Frequency
All these depend on each other
The waves produced by a motorboat sailing in water are
transverse
longitudinal
longitudinal and transverse
stationary
Two springs are connected to a block mass M placed on a frictionless surface as shown in figure. If both the springs have a spring constant k, the frequency of oscillation of the block is
An organ pipe closed at one end has a fundamental frequency of 1500 Hz. The maximum number of overtones generated by this pipe which a normal can hear is
14
13
6
9
Switch
