How does an electric generator work? (Class 10)
Answers
✈ Electric motor:
A motor is a device which converts electrical energy into mechanical energy.
✈ Principle of motor :
A motor works on the principle that when a rectangular coil is placed in a magnetic field and current is passed through it. A force acts on the coil which rotates it continuously.
✈ Construction and Working of motor:
When electric current is passed into the rectangular coil, this current produces a magnetic field around the coil.
The magnetic field of horse shoe-type magnet then interacts with the magnetic field of the coil and causes the coil to rotate continuously.
If ABCD is in horizontal position current from battery enters the coil through brush B1, and commutator half ring C:. The current flows in the direction ABCD and leaves via ring and brush B2.
The direction of current is from A to B, the direction of current is from C to D. The force on side AB of the coil is in the downward direction. Whereas the force on the side CD of the coil is in the upward direction. ABCD rotate in anti-clockwise direction.
While rotating when the coil reaches vertical position then the brushes B1 and B2 will touch the gap between the commutator rings and current to the coil is cut off. But the coil does not stop rotating because it has already gained momentum.
The coil CD comes on the left side and AB comes to the right side. Again they come in contact with brush B1. Current direction is reversed.
The reversing of current in the coil is repeated after every half rotation due to which the coil continue to rotate as long as current from the batter is passed through it. The rotating shaft of electric motor can drive a large number of machines which are connected to it.
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Here is your answer -
Electric generators are based on the principle of electromagnetic induction and converts mechanical energy into electrical energy.
An electric generator consists of a rotating rectangular coil placed between the two poles of a permanent magnet.
The two rings R1 and R2 are internally attached to an axle. The axle may be mechanically rotated from outside to rotate the coil inside the magnetic field.
Outer ends of the two brushes B1 and B2 are connected to the galvanometer to show the flow of current in the given external circuit.
When the axle is rotated, arm AB moves up (and the arm CD moves down) in the magnetic field produced by the permanent magnet. Let us say that the coil ABCD is rotated clockwise.
By applying Fleming’s right-hand rule, the induced currents are set up in these arms along the directions AB and CD. Thus, an induced current flows in the direction ABCD. If there are more turns in the coil, the current generated in each turn adds up to give a large current through the coil.
After half rotation, CD and AB reverse direction, and thus, CD starts moving up and AB starts moving down. As a result, the directions of the induced currents in both the arms change.
Such a current which changes direction after equal intervals of time is called an alternating current. Thus, this device is called an AC generator.
To get a direct current, a split-ring type commutator must be used. The generator is thus called a DC generator.
The difference between direct and alternating currents is that the direct current always flows in one direction, whereas the alternating current reverses its direction periodically.
