Tag: coherence

Questions Related to coherence

Coherence is a measure of

physics superposition of waves coherence young's double slit experiment interference

  1. capability of producing interference by wave

  2. waves being diffracted

  3. waves being reflected

  4. waves being refracted

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Correct Option: A
Explanation:

Interference is a phenomenon in which two waves superpose to form a resultant wave of greater or lower amplitude.

If the sources are coherent, the interference pattern obtained is more ordered, with definite spacing between fringes. 
Thus coherence is a measure of capability of producing interference of wave.

The phenomenon of interference is shown by:

physics superposition of waves coherence young's double slit experiment interference

  1. longitudinal mechanical waves only

  2. electromagnetic waves only

  3. transverse mechanical waves only

  4. all the above types of waves

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Correct Option: D
Explanation:

All of the above type of waves.


Interference of a wave is the phenomenon that usually happens when the two waves reinforce,while travelling in the same medium. The interference of waves causes the medium to take on a shape that results from the net effects of the two individual waves simultaneously acting upon the particles of the medium.

Two coherent sources of light can be obtained by

physics superposition of waves coherence young's double slit experiment interference

  1. two different lamps

  2. two different lams of same power and same colour

  3. two different lamps of same power

  4. none of these

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Correct Option: D
Explanation:

Two sources are said to be coherent if they have exactly same frequency and have zero or constant phase difference. Two coherent source cannot be obtained from two different light sources.

Two light sources are said to be coherent if they are obtained from:

physics superposition of waves coherence young's double slit experiment interference

  1. two ordinary bulbs emitting light of different wavelengths

  2. a single point source

  3. a wide source

  4. two independent point sources emitting light of the same wavelength

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Correct Option: B

Interference occurs in which of the following waves?

physics superposition of waves coherence young's double slit experiment interference

  1. Transverse

  2. Electromagnetic

  3. Longitudinal

  4. All of these

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Correct Option: D
Explanation:

Since, interference occurs both in sound and light waves so it will occur in all the forms of waves given.

The sources which can give sustained interference are:

physics superposition of waves coherence young's double slit experiment interference

  1. two independent laser sources

  2. two independent light bulbs

  3. two light sources of very large width

  4. two sources far away from one other

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Correct Option: A
Explanation:

Laser sources produce light waves which are coherent. As sustained interference takes place between waves, which are coherent, we can use two independent laser sources for the same.

In a Laser beam the photons emitted are :

physics superposition of waves coherence young's double slit experiment interference

  1. incoherent

  2. coherent

  3. of same velocity

  4. of same wavelength

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Correct Option: B
Explanation:

LASER refers to light amplification based on the stimulated emission of Radiation. It emits light coherently. Thus the photons emitted in a laser beam are coherent.

Two waves having the same wavelength and amplitude but having a constant phase difference with time are known as :

physics superposition of waves coherence young's double slit experiment interference

  1. identical waves

  2. incoherent waves

  3. coherent waves

  4. collateral waves

Show answer
Correct Option: C
Explanation:

When the light waves are emitted from a single source and they have a constant phase difference between them then the waves are said to be coherent.
Option C is correct .

Light waves spreading from two sources produce steady interference only if they have:

physics superposition of waves coherence young's double slit experiment interference

  1. congruence

  2. coherence

  3. same intensity

  4. same amplitude

Show answer
Correct Option: B
Explanation:

Interference refers to the interaction of waves that are correlated of coherent with each other. Sustained interference takes place between waves which are coherent.

Interference of light from two sources can be observed if 

physics superposition of waves coherence young's double slit experiment interference

  1. The sources are independent.

  2. The sources are of different frequencies and random phases.

  3. The sources are of different frequency.

  4. The sources are coherent.

Show answer
Correct Option: D
Explanation:

Interference of light from two sources can be observed if the sources are coherent . It means that the phase difference between two sources must be constant with time . Two independent sources can't produce an interference pattern .