Assertion:  A beam of charged particles is employed in the treatment of cancer. 

Reason: Charged particles on passing through a material medium lose their energy by causing ionization of the atoms along their path.

• if both assertion and reason are true and the reason is the correct explanation of the assertion

• if both assertion and reason are true and the reason is not the correct explanation of the assertion

• if assertion is true but reason is false

• if both assertion and reason are false statements

Assertion: Coloured spectrum is seen when we look through a muslin cloth. 

Reason:  It is due to the diffraction of white light on passing through fine slits

• If both the assertion and reason are true and reason is a correct explanation of the assertion

• If both assertion and reason are true but assertion is not a correct explanation of the assertion.

• If the assertion is true but the reason is false.

• If both assertion and reason are false.

Assertion:  When tiny circular obstacle is placed in the path of light from some distance, a bright spot is seen at the centre of the shadow of the obstacle. 

Reason: Destructive interference occurs at the centre of the shadow.

• If both the assertion and reason are true and reason is a correct explanation of the assertion.

• If both assertion and reason are true but assertion is not a correct explanation of the assertion.

• If the assertion is true but the reason is false

• If both assertion and reason are false.

Assertion:  S.I. units are logical and coherent. 

Reason: S.l. system of units is a rationalised system.

• If both the assertion and reason are true and reason is a correct explanation of the assertion.

• If both assertion and reason are true but assertion is not a correct explanation of the assertion.

• If the assertion is true but the reason is false.

• If both assertion and reason are false.

185.

Two coherent monochromatic light beams of amplitude 3 and 5 units are superposed. The maximum and minimum possible intensities in the resulting beams are in the ratio

• 4 : 2

• 16 : 1

• 8 : 2

• 4 : 2

Assertion:  Skiers uses air glasses. 

Reason:  Light reflected by snow is partially polarised.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If assertion is false but reason is true.

The distance between two coherent sources is 1 mm. The screen is placed at a distance of 1 m from the sources. If the distance of the third bright fringe is 1.2 mm from the central fringe, the wavelength of light used is

• 4000 Å

• 5000 Å

• 6000 Å

• 7200 Å

Two polaroids are crossed. If now one of them is rotated through 30° and unpolarized light of intensity IO is incident on the first polaroid, then the intensity of transmitted light will be

• I_o/4

• 3I_o/4

• 3I_o/8

• I_o/8

A wavefront is represented by the plane y = 3-x. The propagation of the wave takes place at

• 45° with x direction

• 135° with x direction

• 60° with x direction

• No sufficient data

The intensity ratio of two coherent sources of light is P. They are interfering in the same region and produce an interference pattern. Then the fringe visibility is

• $\frac{1+\mathrm{P}}{2\sqrt{\mathrm{P}}}$

• $\frac{2\sqrt{\mathrm{P}}}{1+\mathrm{P}}$

• $\frac{\mathrm{P}}{1+\mathrm{P}}$

• $\frac{2\mathrm{P}}{1+\mathrm{P}}$