Colours of thin films result from

Or

On a rainy day, a small oil film on water show brilliant colours. This is due to

1. Dispersion of light

2. Interference of light

3. Absorption of light

4. Scattering of light

In a Young's double slit experiment the intensity at a point where the path difference is $\frac{\lambda }{6}$ ($\lambda$ being the wavelength of the light used) is I. If I₀ denotes the maximum intensity, $\frac{I}{I_0}$ is equal to

1. $\frac{1}{\sqrt{2}}$

2. $\frac{\sqrt{3}}{2}$

3. 1/2

4. 3/4

An optically active compound 

1. Rotates the plane polarised light

2. Changes the direction of polarised light

3. Does not allow plane polarised light to pass through

4. None of the above

In a Young's experiment, the separation between the slits is 0.10 mm, the wavelength of light used is 600 nm and the interference pattern is observed on a screen 1.0 m away. Find the separation between the successive bright fringes.

1. 6.6 mm

2. 6.0 mm

3. 6 m

4. 6 cm.

Intensities of the two waves of light are I and 4I. The maximum intensity of the resultant wave after superposition is 

1. 5I

2. 9I

3. 16I

4. 25I

Two polaroids are placed in the path of unpolarized beam of intensity I₀ such that no light is emitted from the second polaroid. If a third polaroid whose polarization axis makes an angle $\theta$ with the polarivation axis of first polaroid. is placed between these polaroids then the intensity of light emerging from the last polaroid will be 

1. $\left(\frac{I_0}{8}\right){\sin }^{2}2\theta$

2. $\left(\frac{I_0}{4}\right){\sin }^{2}2\theta$

3. $\left(\frac{I_0}{2}\right){\cos }^4\theta$

4. $I_0{\cos }^4\theta$

In the Young's double slit experiment using a monochromatic light of wavelength $\lambda$, the path difference (in terms of an integer n) corresponding to any point having half the peak intensity is 

1. $(2n+1)\frac{\lambda }{2}$

2. $(2n+1)\frac{\lambda }{4}$

3. $(2n+1)\frac{\lambda }{8}$

4. $(2n+1)\frac{\lambda }{16}$

Young's double slit experiment is carried out by using green, red and blue light, one color at a time. The fringe widths recorded are ${\beta }_{\mathrm{G}}, {\beta }_R$ and ${\beta }_B ,$ respectively. Then

1. ${\beta }_G>{\beta }_B>{\beta }_R$

2. ${\beta }_B>{\beta }_C>{\beta }_R$

3. ${\beta }_R>{\beta }_B>{\beta }_G$

4. ${\beta }_R>{\beta }_G>{\beta }_B$

In a Young's double slit experiment, the fringe width is found to be 0.4 mm. If the whole apparatus is immersed in water of refractive index 4/3 without disturbing the geometrical arrangement, the new fringe width will be 

1. 0.30 mm

2. 0.40 mm

3. 0.53 mm

4. 450 micron

Two light sources are said to be coherent if they are obtained from

1. Two independent point sources emitting light of the same wavelength

2. A single point source

3. A wide source

4. Two ordinary bulbs emitting light of different wavelengths