51.

A ray of light is incident normally on one face of a right angled isosceles prism. It then grazes the hypotenuse. The refractive index of the material of the prism is

• 1.33

• 1.414

• 1.5

• 1.732

Two thin equiconvex lenses each of focal length 0.2 m are placed coaxially with their optic centres 0.5 m apart. Then the focal length of the combination is

• − 0.4 m

• 0.4 m

• − 0.1 m

• 0.1 m

A prism of a certain angle deviates the red and blue rays by 8° and 12° respectively. Another prism of the same angle deviates the red and blue rays by 10° and 14° respectively. The prisms are small angled and made of different materials. The dispersive powers of the materials of the prisms are in the ratio

• 5 : 6

• 9 : 11

• 6 : 5

• 11 : 9

When the angle of incidence is 60° on the surface of a glass slab, it is found that the reflected ray is completely polarised. The velocity of light in glass is

• $\sqrt{2} \times {10}^8 {\mathrm{ms}}^{-1}$

• $\sqrt{3} \times {10}^8 {\mathrm{ms}}^{-1}$

• 2 × 10⁸ ms^-1

• 3 × 10⁸ ms^-1

A 20 cm length of a certain solution causes right handed rotation of 38°. A 30 cm length of another solution causes left handed rotation of 24°. The optical rotation caused by 30 cm length of a mixture of the above solutions in the volume ratio 1 : 2 is 

• left handed rotation of 14°

• right handed rotation of 14°

• left handed rotation of 3°

• right handed rotation of 3°

The volume of a nucleus is directly proportional to

• A

• A³

• $\sqrt{\mathrm{A}}$

• A^1/3

An electron is

• a hadron

• a baryon

• a nucleon

• a lepton

Minority carriers in a p-type semiconductor are

• free electrons

• holes

• neither holes nor free electrons

• both holes and free electrons

In a reverse biased diode when the applied voltage changes by 1 V, the current is found to change by 0.5 µA. The reverse bias resistance of the diode is

• 2 × 10⁵ Ω

• 2 × 10⁶ Ω

• 200 Ω

• 2 Ω

The truth table given below is for (A and B are the inputs, Y is the output)

• NOR

• AND

• XOR

• NAND