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

1.	Interference
2.	Diffraction
3.	Photoelectric effect
4.	Polarisation

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

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

(1) cL

(2) $\frac{L}{c}$

(3) $\frac{c}{L}$

(4) $\frac{1}{Lc}$

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

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

(1) $(2n-1)\frac{\lambda }{4}$

(2) $(2n-1)\frac{\lambda }{2}$

(3) $n\lambda$

(d) $(2n+1)\frac{\lambda }{2}$

Soap bubble appears coloured due to the phenomenon of:
1. Interference
2. Diffraction
3. Dispersion
4. Reflection

Which of the following statements indicates that light waves are transverse? 

Interference was observed in interference chamber when the air was present, now the chamber is evacuated and if the same light is used, a careful observer will see

(1) No interference

(2) Interference with bright bands

(3) Interference with dark bands

(4) Interference in which width of the fringe will be slightly increased

Ray diverging from a point source forms a wavefront that is:

1. cylindrical.

2. spherical.

3. plane.

4. cubical.

Two coherent sources have intensity in the ratio of $\frac{100}{1}$. Ratio of (intensity)_max/(intensity)_min is: 
1. $\frac{1}{100}$
2. $\frac{1}{10}$
3.$\frac{10}{1}$
4. $\frac{3}{2}$