short notes of electric motor with figure, principal, construction and working and uses.
Answers
Answer:
Working of the electric motor:
According to Fleming's left-hand rule, the force experienced by arm AB is in the downward direction and arm CD in the upward direction. Both these forces are equal and opposite. This force rotates the coil in the anticlockwise direction until the coil is vertical.
Answer ::
Electric motor: It is a device which converts electrical energy into mechanical energy. Construction: Electric motor consists of following parts:
(I)Rectangular coil: A large number of turns of insulated copper wire wound on iron core in rectangular shape forms a coil ABCD as shown in figure.
(ii)Strong magnet: The coil is placed in between two pole pieces (N and S) of a ii. horse shoe magnet which strong provides a strong magnetic field. The sides AB and CD are perpendicular to the direction of magnetic field.
(iii)Split ring: It consists of two halves of a metallic ring (R1 and R2). The ends of the coil are connected to these rings. The outer conducting surfaces of spilt rings R1 and R2 are in contact with the two stationary carbon brushes. Spilt rings reverse the direction of current in the coil. (iv) Brushes: Two carbon brushes B and iv. B2 are used to press the split rings.
(v)Axle: The two halves of the rings have resistive coating in their inner surfaces and are tightly fitted on the axle. The V. main function of axle is to rotate with the coil.
(vi). Battery: The battery supplies the current to the coil.
Working:
(i)When the circuit is completed, the current passes through the brush B from A to B in branch AB.
(ii)As, the magnetic field acts from north pole to south pole, according to Fleming's left hand rule, the force experienced by arm AB is in the downward direction and arm CD is in the upward direction.
(iii)Both these forces are equal in magnitude and opposite in direction and hence, the coil rotates in anticlockwise .
(iv)After half rotation, the split rings R2 and R1 come in contact with brushes B1 and B2 respectively.
(v) Again the current starts passing through the coil in opposite direction.
(vi)The force acting on branch BA is upward and DC is downward, this force again moves the coil in anticlockwise direction.
(vii) This shows that the current in the loop ABCD is reversed after every half rotation, and the loop continues to rotate in same direction.
- (viii)Thus, the coil rotates with the help of electrical energy.