Dual Nature of Radiation and Matter — Physics STD 12 Science — Question

A man cannot see clearly the objects beyond a distance of 20 cm from his eyes. To see distant objects clearly he must use which kind of lenses and of what focal length

(a) 100 cm convex

(b) 100 cm concave

(c) 20 cm convex

(d) 20 cm concave

When potential difference is applied across an electrolyte, then Ohm's law is obeyed at:

An electric dipole is placed in a uniform electric field. The net electric force on the dipole.

If the operating potential of an X-ray tube is 50 kV, the velocity of X-rays coming out of it is

(a) 4

(b) 3

(c)

(d) 3 m/s

200 MeV of energy may be obtained per fission of . A reactor is generating 1000 kW of power. The rate of nuclear fission in the reactor is

(a) 1000

(b) 2

(c) 3.125

(d)  931

A sphere is rolled on a rough horizontal surface. It gradually slows down and stops. The force of friction tries to:

1. Decrease the linear velocity.
2. Increase the angular velocity.
3. Increase the linear momentum.
4. Decrease the angular velocity.

The inductance of a closed-packed coil of 400 turns is 8 mH. A current of 5 mA is passed through it. The magnetic flux through each turn of the coil is

(a)

(b)

(c)

(d)

The valence band and conduction band of a solid overlap at low temperature, the solid may be

(a) A metal

(b) A semiconductor

(c) An insulator

(d) None of these

A constant current is flowing through a long straight conductor, then the graph showing change in produced magnetic field B with distance r is:

A thin equiconvex lens is made of glass of refractive index 1.5 and its focal length is 0.2 m, if it acts as a concave lens of 0.5 m focal length when dipped in a liquid, the refractive index of the liquid is

(a)

(b)

(c)

(d)