In a single-slit diffraction experiment, the width of the slit is reduced by half. Which of the following needs to be done if the width of the central maxima has to remain the same

1. Reduce the distance between the slit and screen by half

2. Reduce the distance between the slit and the screen to ${\left(\frac{1}{4}\right)}^{th}$ the original separation

3. Double the distance between the slit and the screen

4. No need to do anything, as the width of the central maxima does not depend on the slit width

In Young's experiment the wavelength of red light is 7.5 x 10^-5 cm. and that of blue light 5.0 x 10^-5 cm. The value of n for which (n+1)^th the blue bright band coincides with n^th red band is -

1. 8

2. 4

3. 2

4. 1

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. ${\beta }_R>{\beta }_G>{\beta }_B$