For a parallel beam of monochromatic light of wavelength diffraction is produced by a single slit whose width 'a' is of the order of the wavelength of the light. If 'D' is the distance of the screen from the slit, the width of the central maxima will be

(1)2Dλ/a

(2)Dλ/a

(3)Da/λ

(4)2Da/λ

In a double-slit experiment, the two slits are 1 mm apart and the screen is placed 1 m away. A monochromatic light of wavelength 500 nm is used. What will be the width of each slit for obtaining ten maxima of double-slit within the central maxima of a single-slit pattern?

1. 0.2 mm

2. 0.1 mm

3. 0.5 mm

4. 0.02 mm

At the first minimum adjacent to the central maximum of a single slit diffraction pattern, the phase difference between the Huygen's wavelet from the edge of the slit and the wavelet from the midpoint of the slit is

(1) π/4 radian

(2) π/2 radian

(3) π radian

(4) π/8 radian

A beam of light of 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 first dark fringes on either side of the central bright fringe is
                      
1. 1.2cm

2. 1.2mm

3. 2.4cm

4. 2.4mm

In the Young's double-slit experiment, the intensity of light at a point on the screen (where the path difference is λ ) is K where λ being the wavelength of light used. The intensity at a point where the path difference is λ /4 will be 

(1) K

(2) K/4

(3) K/2

(4) zero

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

In a double slit experiment, the distance between the slits is 3 mm and the slits are 2 m away from the screen one due to light with wavelength 480 nm, and the other due to light with wavelength 600 nm. What is the separation on the screen between the fifth order bright fringes of the two interference patterns ?

1. $4\times {10}^{-4}$

2. $9\times {10}^{-4}$

3. $3\times {10}^{-4}$

4. $5\times {10}^{-4}$

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 have the same colour

(4) None of the above

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