51.

In Young's experiment, if separation between slits is made half, then fringe width will become

• double

• four times

• half

• remains same

Resolving power of human eye is

• 0.1"

• 1"

• 0.1'

• 1'

If distance between light source and screen is doubled, then intensity of light will become

• half

• double

• remains same

• 1/4 th

The colour of a red cloth in green light appears

• red

• green

• orange

• black

If dopping in the P region is high, then N region

• depletion layer will be more towards P

• depletion layer will be more towards N

• depletion layer will remain unchanged

• None of the above

For a triode valve µ = 50, ΔV_g = 0.2 V, then value of ΔV_p is

• 5 V

• 10 V

• 0.2 V

• 50 V

Focal length of a lens is +10 cm and its refractive index is 1.4, it is dipped in a liquid of refractive index 1.6, then its focal length becomes

• - 16 cm

• + 32 cm

• + 16 cm

• - 32 cm

If focal length of convex lens is 9 cm and that of a concave lens is -18 cm, then focal length of combination is

• + 9 cm

• - 18 cm

• - 9 cm

• + 18 cm

Two mirror are put at an angle of 60°C, then number of image of an object placed between the mirrors is

• 3

• 4

• 5

• 6

Speed of light in vacuum is

• $\frac{1}{\sqrt{{\mathrm{\mu }}_0{\mathrm{\epsilon }}_0}}$

• $\sqrt{\frac{{\mathrm{\mu }}_0}{{\mathrm{\epsilon }}_0}}$

• $\sqrt{{\mathrm{\mu }}_0{\mathrm{\epsilon }}_0}$

• $\sqrt{\frac{{\mathrm{\epsilon }}_0}{{\mathrm{\mu }}_0}}$