In Young’s experiment, monochromatic light is used to illuminate the two slits A and B. Interference fringes are observed on a screen placed in front of the slits. Now if a thin glass plate is placed normally in the path of the beam coming from the slit 

(1) The fringes will disappear

(2) The fringe width will increase

(3) The fringe width will decrease

(4) There will be no change in the fringe width but the pattern shifts

Two slits, 4 mm apart, are illuminated by light of wavelength 6000 Å. What will be the fringe width on a screen placed 2m from the slits 

(1) 0.12 mm

(2) 0.3 mm

(3) 3.0 mm

(4) 4.0 mm

In the Young’s double slit experiment with sodium light. The slits are 0.589 m a part. The angular separation of the third maximum from the central maximum will be (given λ = 589 nm) 

(1) ${\sin }^{-1}(0.33\times {10}^8)$

(2) ${\sin }^{-1}(0.33\times {10}^{-6})$

(3) ${\sin }^{-1}(3\times {10}^{-8})$

(4) ${\sin }^{-1}(3\times {10}^{-6})$

If the sodium light in Young’s double slit experiment is replaced by red light, the fringe width will

(1) Decrease

(2) Increase

(3) Remain unaffected

(4) First increase, then decrease

In Young’s double-slit experiment the wavelength of light was changed from 7000 Å to 3500 Å. While doubling the separation between the slits which of the following is not true for this experiment:

(1) The width of the fringes changes

(2) The colour of bright fringes changes

(3) The separation between successive bright fringes changes

(4) The separation between successive dark fringes remains unchanged

In Young’s double-slit experiment, an interference pattern is obtained on a screen by a light of wavelength 6000 Å, coming from the coherent sources S₁ and S₂. At certain point P on the screen third dark fringe is formed. Then the path difference S₁P – S₂P in microns is 

(1) 0.75

(2) 1.5

(3) 3.0

(4) 4.5

In Young’s double-slit experiment the fringe width is β. If entire arrangement is placed in a liquid of refractive index n, the fringe width becomes 

(1) $\frac{\beta }{n+1}$

(2) nβ

(3) $\frac{\beta }{n}$

(4) $\frac{\beta }{n-1}$

In Young’s double slit experiment, distance between two sources is 0.1 mm. The distance of screen from the sources is 20 cm. Wavelength of light used is 5460 Å. Then angular position of the first dark fringe is 

1. 0.08°

2. 0.16°

3. 0.20°

4. 0.32°

In a Young’s double slit experiment, the slit separation is 0.2 cm, the distance between the screen and slit is 1m. Wavelength of the light used is 5000 Å. The distance between two consecutive dark fringes (in mm) is 

(1) 0.25

(2) 0.26

(3) 0.27

(4) 0.28

A star emitting light of wavelength 5896 Å is moving away from the earth with a speed of 3600 km/sec. The wavelength of light observed on earth will 

(1) Decrease by 5825.25 Å

(2) Increase by 5966.75 Å

(3) Decrease by 70.75 Å

(4) Increase by 70.75 Å

(c = 3 × 10⁸ m/sec is the speed of light)