In Young’s double slit experiment. the slits are 2 mm apart and are illuminated by photons of two wavelengths , λ1= 12000Å and , λ2= 10000Å. At what minimum distance from the common central bright fringe on the screen 2m from the slit will a bright fringe from one interference pattern coincide with a bright fringe from the other?

(a) 8mm

(b) 6mm

(c) 4 mm

(d) 3mm

Concept Questions :-

Young Double slit experiment
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A parallel beam of fast-moving electrons is incident normally on a narrow slit. A fluorescent screen is placed at a large distance from the slit. If the speed of the electrons is increased, then which of the following statements is correct?

(a) Direction pattern is not observed on the screen in the case of electrons

(b) The angular width of the central maximum of the diffraction pattern will increase

(c) The angular width of the central maximum will decrease

(d) The angular width of the central maximum will be unaffected

Concept Questions :-

Superposition principle
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Two coherent sources of light can be obtained by

(1) Two different lamps

(2) Two different lamps but of the same power

(3) Two different lamps of the same power and having the same colour

(4) None of the above

Concept Questions :-

Huygens' principle
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By Huygen's wave theory of light, we cannot explain the phenomenon of 

(1) Interference

(2) Diffraction

(3) Photoelectric effect

(4) Polarisation

Concept Questions :-

Huygens' principle
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Two coherent monochromatic light beams of intensities I and 4I are superposed. The maximum and minimum possible intensities in the resulting beam are 

(1) 5I and I

(2) 5I and 3I

(3) 9I and I

(4) 9I and 3I

Concept Questions :-

Superposition principle
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If L is the coherence length and c the velocity of light, the coherent time is 

(1) cL

(2) Lc

(3) cL

(4) 1Lc

Concept Questions :-

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If the amplitude ratio of two sources producing interference is 3 : 5, the ratio of intensities at maxima and minima is 

(1) 25 : 16

(2) 5 : 3

(3) 16 : 1

(4) 25 : 9

Concept Questions :-

Superposition principle
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For constructive interference to take place between two monochromatic light waves of wavelength λ, the path difference should be 

(1) (2n1)λ4

(2) (2n1)λ2

(3) nλ

(d) (2n+1)λ2

Concept Questions :-

Young Double slit experiment
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Soap bubble appears coloured due to the phenomenon of 

(1) Interference

(2) Diffraction

(3) Dispersion

(4) Reflection

Concept Questions :-

Interference vs Diffraction
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Which of the following statements indicates that light waves are transverse 

(1) Light waves can travel in vacuum

(2) Light waves show interference

(3) Light waves can be polarized

(4) Light waves can be diffracted

Concept Questions :-

Polarization of light
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