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) 0.313°

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 slit of width a is illuminated by white light. For red light (λ = 6500 Å), the first minima is obtained at θ = 30°. Then the value of a will be 

(1) 3250 Å

(2) 6.5 × 10^–4 mm

(3) 1.24 microns

(4) 2.6 × 10^–4 cm

What will be the angular width of central maxima in Fraunhoffer diffraction when light of wavelength $6000\AA$ is used and slit width is 12×10^–5 cm 

(1) 2 rad

(2) 3 rad

(3) 1 rad

(4) 8 rad

A beam of light of wavelength 600 nm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 m away. The distance between the first dark fringes on either side of the central bright fringe is 

(1) 1.2 mm

(2) 1.2 cm

(3) 2.4 cm

(4) 2.4 mm

Direction of the first secondary maximum in the Fraunhofer diffraction pattern at a single slit is given by (a is the width of the slit) 

(1) $a\sin \theta =\frac{\lambda }{2}$

(2) $a\cos \theta =\frac{3\lambda }{2}$

(3) $a\sin \theta =\lambda$

(4) $a\sin \theta =\frac{3\lambda }{2}$

A parallel monochromatic beam of light is incident normally on a narrow slit. A diffraction pattern is formed on a screen placed perpendicular to the direction of the incident beam. At the first minimum of the diffraction pattern, the phase difference between the rays coming from the edges of the slit is

(1) $0$

(2) $\frac{\pi }{2}$

(3) $\pi$

(4) 2$\pi$