Assertion The resolving power of a telescope is more if the diameter of the objective lens is more. 

Reason Objective lens of large diameter collects more light.

1. Both the assertion and the reason are true and the reason is a correct explanation of the assertion
2. Both the assertion and reason are true but the reason is not a correct explanation of the assertion
3. Assertion is true but the reason is false
4. Both the assertion and reason are false

Assertion: In Young's double-slit experiment the two slits are at a distance d apart. The interference pattern is observed on a screen at a distance D from the slits and a dark fringe is observed. The wavelength of the wave is proportional to the square of the distance between two slits.

Reason: For a dark fringe, intensity is zero.

1. Both the assertion and the reason are true and the reason is a correct explanation of the assertion.
2. Both the assertion and reason are true but the reason is not a correct explanation of the assertion.
3. Assertion is true but the reason is false.
4. Both the assertion and reason are false.

Assertion: It is not possible to have interference between the waves produced by two violins. 

Reason: For interference of two waves the phase difference between the waves must remain constant.
1. Both the assertion and the reason are true and the reason is a correct explanation of the assertion.
2. Both the assertion and reason are true but the reason is not a correct explanation of the assertion.
3. Assertion is true but the reason is false.
4. Both the assertion and reason are false.

Assertion: To observe the diffraction of light the size of the obstacle/aperture should be of the order of 10^-7 m.
Reason: 10^-7 m is the order of the wavelength of visible light.
1. Both the assertion and the reason are true and the reason is a correct explanation of the assertion.
2. Both the assertion and reason are true but the reason is not a correct explanation of the assertion.
3. Assertion is true but the reason is false.
4. Both the assertion and reason are false.

Assertion: Radio waves can be polarised.
Reason: Sound waves in air are longitudinal in nature.
1. Both the assertion and the reason are true and the reason is a correct explanation of the assertion.
2. Both the assertion and reason are true but the reason is not a correct explanation of the assertion.
3. Assertion is true but the reason is false.
4. Both the assertion and reason are false.

Assertion (A): An electron microscope can achieve better resolving power than an optical microscope.

Reason (R): The de Broglie's wavelength of the electrons emitted from an electron gun is much less than the wavelength of visible light.

1. Both the assertion and the reason are true and the reason is a correct explanation of the assertion.
2. Both the assertion and reason are true but the reason is not a correct explanation of the assertion.
3. Assertion is true but the reason is false.
4. Both the assertion and reason are false.

Two Sources ${\mathrm{S}}_1 \mathrm{and} {\mathrm{S}}_2$ of intensity $I_1 and l_2$ are in front of a screen [Fig.(a)]. The pattern of intensity distribution seen in the central portion is given by Fig.(b).

In this case, which of the following statements are true?

(a) $S_{1}and S_2$ have the same intensities
(b) $S_{1}and S_2$ have a constant phase difference
(c) $S_{1}and S_2$ have the same phase
(d) $S_{1}and S_2$ have the same wavelength 

1. (a, b, c)

2. (a, b, d)

3. (b, c, d)

4. (c, d)

Consider sunlight incident on a pinhole of width ${10}^3$ $\stackrel{\circ }{A}$. The image of the pinhole seen on a screen shall be:

(a) a sharp white ring
(b) different from a geometrical image
(c) a diffused central spot, white in colour
(d) diffused coloured region around a sharp central white spot

1. (a, c)

2. (a, d)

3. (b, d)

4. (b, c)

Consider the diffraction pattern for a small pinhole. As the size of the hole is increased:

(a) the size decreases
(b) the intensity increases
(c) the size increases
(d) the intensity decreases

1. (a, b)

2. (a, c)

3. (b, d)

4. (c, d)