Magnetism And Matter — Physics STD 12 Science — Question

If critical angle for a material to air is 30^o, the refractive index of the material will be

(a) 1.0

(b) 1.5

(c) 2.0

(d) 2.5

To deposit one gm equivalent of an element at an electrode, the quantity of electricity needed is

(a) One ampere

(b) 96000 amperes

(c) 96500 farads

(d) 96500 coulombs

A rectangular coil 20 cm × 20 cm  has 100 turns and carries a current of 1 A. It is placed in a uniform magnetic field       B  = 0.5 T with the direction of magnetic field parallel to the plane of the coil. The magnitude of the torque required to hold this coil in this position is

(a) Zero

(b) 200 N-m

(c) 2 N-m

(d) 10 N-m

A long solenoid has a radius a and number of turns per unit length is n. If it carries a current i, then the magnetic field on its axis is directly proportional to

(a) ani

(b) ni

(c)

(d)

According to Kirchhoff's law, at any junction in an electric circuit:

Two equally charged spheres attract each other. Now if they touch each other then they will _____?

Force on any charge due to a number of other charges is the _____ of all the forces on that charge taken one at a time.

Figure shows a small wheel fixed coaxially on a bigger one of double the radius. The system rotates about the common axis. The strings supporting A and B do not slip on the wheels. If x and y be the distance travelled by A and B in the same time interval, then:

1. x = 2y
2. x = y
3. y = 2x
4. None of these.

The potential difference applied to an X-ray tube is increased. As a result, in the emitted radiation:

1. The intensity increases.
2. The minimum wavelength increases.
3. The intensity remains unchanged.
4. The minimum wavelength decreases.

The binding energy of deuteron  is 1.112 MeV per nucleon and an α - particle  has a binding energy of 7.047 MeV per nucleon. Then in the fusion reaction  the energy Q released is

(a) 1 MeV

(b) 11.9 MeV

(c) 23.8 MeV

(d) 931 MeV