Describe the principle, construction and working of an electric generator with a figure.

v Principle

Electric generator is a device which works on the principle of Electromagnetic Induction. The main point here to note and keep in mind is that a changing magnetic field can induce current in a conductor.

v Construction of a simple generator

•A loop ABCD of an insulated copper wire is placed in a permanent magnetic field such that part BC and AD of the wire is perpendicular to the applied magnetic field.

•The ends of this wire are connected to two semicircular full rings R₁ and R₂ which are adjusted on an axle for their easy rotation.

•The outer part of the rings are connected to Galvanometer by stationary brushes B₁ and B₂.

The construction of the motor and generator is same, just batteries in motor are replaced by galvanometer to detect current.

Here R₁ and R₂ two full rings and B₁ and B₂ are brushes.

v Working of the generator

•Inside the generator there is a conductor wire ABCD placed between fixed strong magnets.

•A mechanical rotation is provided to the loop wire ABCD.

•The wire is already placed in strong magnetic field of a strong magnet.

•So, the motion of the wire changes the magnetic field associated with the conductor loop ABCD and induce an electric current in the wire.

•One important point to notice is that generator provides an alternating current because which can be explained as follow: As the part AB go up CD come down, which induce the current in one direction. But as the AB part come down CD part go up, which induces the current in opposite direction. If the wire ABCD is connected to full rings it will produce Alternating current but if they are connected to half rings they will generate only Direct Current.

•That is how alternating current/Direct current is produced from a generator. The direction of induced current is determined by Fleming's right-hand rule.