Question

The armature is mounted on a spindle so that it can rotate between the concave

pole pieces N and S of powerful horse-shoe magnet. The two ends of the armature

coil are soldered to the two halves of a split ring commutator. The two carbon

brushes are made to press lightly against the split rings by means of springs. The

purpose of the split ring is to reverse the direction of current through coil after

every half rotation. The armature is free to rotate about an axis which is

perpendicular to the magnetic field. The battery which supplies the electric current

to the armature is connected across the carbon brushes. A motor converts

electrical energy to mechanical energy. The electric current obtained from a

battery is direct current. The speed of rotation of the coil can be increased by

increasing the strength of magnetic field, number of turns of coil and current in

coil. The strength of the magnetic field is expressed in terms of SI unit, Tesla.

(i) The role of the split ring commutator is

(a) to reverse the direction of current through coil after every half rotation

(b) to increase the flow of current

(c) to produce magnetic effect

(d) to reduce the resistance

(ii) SI unit of strength of magnetic field is

(a) cm

(b) dioptre

(c) mA

(d) Tesla

(iii) The rectangular coil of insulated copper wire is

(a) earth wire

(b) armature

(c) fuse

(d) none of these

(iv) The speed of rotation of the coil can be increased by increasing

(a) the strength of magnetic field

(b) number of turns of coil

(c) current in the coil

(d) all of the above

(v) The rule that helps us to find the direction of magnetic field, the direction of

current and the direction of motion of the conductor in an electric motor is

(a) Right Hand Thumb rule

(b) Fleming‟s Left Hand rule

(c) Fleming‟s Right Hand rule

(d) Maxwell‟s Cork Screw rule​

Answer 1

Answer:

dont know this ans it is so long

Explanation:

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