XII A- MATTER & MAGNETISM

The strength of the earth’s magnetic field is

• (a) constant everywhere.

• (b) zero everywhere.

• (c) having very high value.

• (d) vary from place to place on the earths surface.

3. Which of the following is responsible for the earth’s magnetic field?

• (а) Convective currents in earth’s core

• (b) Diversive current in earth’s core.

• (c) Rotational motion of earth.

• (d) Translational motion of earth.

The earth behaves as a magnet with magnetic field pointing approximately from the geographic

• (a) North to South

• (b) South to North

• (c) East to West

• (d) West to East

Magnetic moment for solenoid and corresponding bar magnet is

• (a) equal for both

• (b) more for solenoid

• (c) more for bar magnet

• (d) none of these

A magnetic needle is kept in a non-uniform magnetic field. It experiences

• (a) a torque but not a force.

• (b) neither a force nor a torque.

• (c) a force and a torque.

• (d) a force but not a torque

S.I. unit of magnetic dipole moment is ________

A magnetic needle is kept in a uniform magnetic field.It experiences

• a force and a torgue

• a force but not a torque

• a torque but not a force

• neither a force nor a torque

A magnetic needle is kept in a non uniform magnetic field. It experiences

• a force and a torque

• a force but not a torque

• a torque but not a force

• neither a force nor a torque

A bar magnet of magnetic moment m is placed in a uniform magnetic field B.The torque experienced on it is ----

• m.B

• • -m.B

• m x B

• -m x B