A parallel beam of moving electrons is incident normal on a narrow slit. A fluorescent screen is placed at a large distance from the slit. If the slit is further narrowed, then which of the following statement is correct?

1.  The diffraction pattern is not observed on the screen in the case of electrons.

2.  The angular width of the central maximum of the diffraction pattern will increase.

3.  The angular width of the central maximum will decrease.

4.  The angular width of the central maximum will remain the same.

Concept Questions :-

Diffraction
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Difficulty Level:

In Young's double-slit experiment, the slits are 0.4 mm apart and illuminated by photons of two wavelengths ${\lambda }_{1}$ = 600 nm and ${\lambda }_{2}$ = 700nm. At what minimum distance from the common center, bright fringe from one interference pattern coincides with bright fringe from other? (Given that the distance of the screen from the plane of slits is 80cm.)

1.  7.2 mm

2.  6.0 mm

3.  8.4 mm

4.  9.8 mm

Concept Questions :-

Young Double slit experiment
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Difficulty Level:

A diffraction pattern is observed using a beam of red light. What will happen if the red light is replaced by the blue light?

1.  No change takes place

2.  Diffraction bands become narrower

4.  Diffraction pattern disappears

Concept Questions :-

Diffraction
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Difficulty Level:

The phenomenon of polarisation justify which nature of light?

1.  longitudinal

2.  transverse

3.  both

4.  geometrical

Concept Questions :-

Polarization of light
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Difficulty Level:

Two waves of intensity ratio 9:1 interfere to produce fringes in a young's double-slit experiment, the ratio of  intensity at maxima  to the intensity at minima is

1.  4:1

2.  9:1

3.  81:1

4.  9:4

Concept Questions :-

Superposition principle
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Difficulty Level:

nth bright fringe of red light  coincides with (n+1)th bright fringe of green light . The value of n =?

1. 4

2. 5

3. 3

4. 2

Concept Questions :-

Young Double slit experiment

Difficulty Level:

In a double slit experiment to find the separation between slits by displacement method, the separation of images of slits were found to be 16 mm and 9 mm respectively, the actual separation between slits will be

1. 12.5 mm

2. 12 mm

3. 3.5 mm

4. 144 mm

Concept Questions :-

Young Double slit experiment

Difficulty Level:

A double slit of separation 1.5 mm is illuminated by white light (between 4500 $\stackrel{\circ }{\mathrm{A}}$ -7000 $\stackrel{\circ }{\mathrm{A}}$). On a screen 120 cm away coloured interference pattern is formed. If a pinhole is made on this screen at a distance 3.0 mm from the central white fringe, which of the following wavelength will be absent in the transmitted light?

1.  5000 $\stackrel{\circ }{\mathrm{A}}$

2.  6000 $\stackrel{\circ }{\mathrm{A}}$

3.  6500 $\stackrel{\circ }{\mathrm{A}}$

4.  7000 $\stackrel{\circ }{\mathrm{A}}$

Concept Questions :-

Young Double slit experiment

Difficulty Level:

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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Difficulty Level:

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