CRT 4 (CBSE 10th)

Commercial electric motors do not use

• An electromagnet to rotate the armature

• Effectively large number of turns of conducting wire in the current carrying coil

• A permanent magnet to rotate the armature

• A soft iron core on which the coil is wound

The north pole of Earth’s magnet is in :

• Geographical East

• Geographical South

• Geographical West

• Geographical North

The force exerted on a current carrying wire placed in a magnetic field is zero when the angle between wire and the direction of magnetic field is:

(a) 45^o

(b) 60^o

(c) 90^o

(d) 180^o

• 60^o

• 180^o

• 90^o

• 45^o

A Negative charge is moving towards a person. The direction of magnetic field lines will be in

• Clockwise direction

• Anticlockwise direction

• Vertically upward direction

• Vertically downward direction

An electric motor is a device which transforms

• Mechanical energy into electrical energy

• Electrical energy into mechanical energy

• Kinetic energy into potential energy

• Electrical energy into Potential energy

A current flows in a wire running between the S and N poles of a magnet lying horizontally as shown in the figure given.

The force on the wire due to the magnet is directed:

• From N to S

• From S to N

• Vertically downwards

• Vertically upwards

No force acts on a current carrying conductor when it is placed-

• perpendicular to the magnetic field

• parallel to the magnetic field

• far away from the magnetic field

• inside a magnetic field

Who has stated the Right hand Thumb Rule?

• Orsted

• Fleming

• Einstein

• Maxwell

What is the condition of an electromagnetic induction?

• there must be a relative motion between the coil of wire and galvanometer

• there must be a relative motion between

• there must be a relative motion between galvanometer and generator

• there must be a relative motion between the coil of wire and a magnet

The strength of magnetic field inside a long current carrying straight solenoid is

• more at the ends than at the centre

• minimum in the middle

• same at all points

• found to increase from one end to the other