Electric Generator Class 10 - Working, Principle, Diagram - Teachoo

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What is an electric generator?

An electric generator is a device which converts mechanical energy into electrical energy.

It looks like

Principle of Electrical generator

The electrical generator works on the principle that

when a straight conductor is moved in a magnetic field,

then current is induced in the conductor.

Types of Generators

Generator is used to generate electric current.

The electric current can be – AC current or DC current.

Thus, Electric Generators is of two types

AC Generator

– Generates Alternating Current (AC current)
DC Generator

– Generates Direct Current (DC current)

Note

: Whenever Electric Generator is mentioned, we will assume it is a AC Generator

Construction of an AC Electric Generator

AC Electric Generator consists of

Rectangular Coil

of Wire ABCD
A

strong horseshoe magnet

(or 2 different magnets ) – If we take 2 magnets, North Pole of first magnet faces South Pole of Other Magnet, as shown in figure…
The

coil is placed perpendicular to the magnet

as shown in figure
The ends of coil are connected to

two rings – R

1

and R

2
The external conducting edges of rings R

1

and R

2

are connected to two

stationary brushes – B

1

& B

2

respectively
The inner side of the rings is

insulated and attached to the axle

The

axle is mechanically rotated

to rotate the coil
These brushes are attached to a

galvanometer

to show the flow of current in the circuit

Working of an AC Electric Generator

Let’s look at the working of an AC Electric Generator

Suppose axle is rotated clockwise, so coil is also rotated clockwise,

Side AB of Coil moves up and side CD Moves down

Applying

Fleming’s Right Hand Rule

on side

AB,

force is upwards, magnetic field is left to right,

So,

current flows

into the paper i.e. from

A to B
And applying

Fleming’s Right Hand Rule

on side

CD,

force is downwards, magnetic field is left to right,

So,

current flows

out of the paper i.e. from

C to D
Hence, current flows into the Brush B

2

, moves along galvanometer and finally enters B

1

Hence, we say current flows from

B

2

to B

1

in the external circuit.
After

half a rotation,

Side CD Comes on left side and AB Comes on Right Side
Now, on left side CD comes down,

Applying

Fleming’s Right Hand Rule

on side

CD,

force is downwards, magnetic field is left to right,

So,

current flows

out of the paper i.e. from

D to C
And on right side, AB comes up,

Applying

Fleming’s Right Hand Rule

on side

AB,

force is upwards, magnetic field is left to right,

So,

current flows

into the paper i.e. from

A to B
Hence, our circuit is now DCBA,

and current moves in the

opposite direction
Hence, we say current flows from

B

1

to B

2

in the external circuit.
Thus, after every half rotation, direction of current changes.

Hence, Alternating Current is produced

Now, lets look at DC Generator – where current is in one direction

Note: To convert AC generator to DC Generator, we use a

commutator with split rings

(Split, not slip). Just like we do in an Electric Motor

Construction of DC Generator

DC Electric Generator consists of

Rectangular Coil

of Wire ABCD
A

strong horseshoe magnet

(or 2 different magnets ) – If we take 2 magnets, North Pole of first magnet faces South Pole of Other Magnet, as shown in figure…
The

coil is placed perpendicular to the magnet

as shown in figure
The ends of coil are connected to a split ring commutator –

P and Q
The external conducting edges of rings P and Q are connected to two

stationary brushes – X & Y

respectively
The inner side of the rings is

insulated and attached to the axle

The

axle is mechanically rotated

to rotate the coil
These brushes are attached to a

galvanometer

to show the flow of current in the circuit

Working of a DC Electric Generator

Let’s look at the working of a DC Electric Generator

Suppose axle is rotated clockwise, so coil is also rotated clockwise,

Side AB of Coil moves up and side CD Moves down

Applying

Fleming’s Right Hand Rule

on side

AB,

force is upwards, magnetic field is left to right,

So,

current flows

into the paper i.e. from

A to B
And applying

Fleming’s Right Hand Rule

on side

CD,

force is downwards, magnetic field is left to right,

So,

current flows

out of the paper i.e. from

C to D
Hence, current flows into the Brush Y , moves along galvanometer and finally enters X

Hence, we say current flows from

Y to X in the external circuit.
After

half a rotation,

Side CD Comes on left side and AB Comes on Right Side
And

Split ring P is connected to coil CD

and

split ring Q is connected to coil AB.

Which keeps the direction of current in the circuit same.
Hence, current flows from Brush Y , moves along galvanometer and finally enters X

Hence, we say current flows from

Y to X in the external circuit.
Thus, direction of current after every half rotation, direction of current changes.

Hence, Alternating Current is produced

How does Power Stations increase Current and Voltage produced?

They increase current and voltage produced by

Using Electromagnet in place of permanent magnet
Large number of turns of conducting wire(More the turns in wire more the magnetic field)
Soft iron Core on which coil is wound
Rotating the coil faster

Questions

NCERT Question 4 –

The essential difference between an AC generator and a DC generator is that

AC generator has an electromagnet while a DC generator has

permanent magnet.
DC generator will generate a higher voltage.
AC generator will generate a higher voltage.
AC generator has slip rings while the DC generator has a commutator.

View Answer

NCERT Question 6 (b)

–

State whether the following statements are true or false.

An electric generator works on the principle of electromagnetic induction.

View Answer

NCERT Question 16 –

The essential difference between an AC generator and a DC generator is that

View Answer

Question 1 Page 237 –

State the principle of an electric generator.

View Answer

Question 4 Page 237 –

A rectangular coil of copper wire is rotated in a magnetic field. The direction of the induced current changes once in each

(a) two revolutions (b) one revolution

View Answer

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