Electricity Test - 5

In an electric generator, mechanical energy is used to rotate a conductor in a magnetic field to produce electricity.

In an electric generator, the mechanical energy is provided utilizing conventional fuels, which helps rotating the conductor under the influence of magnetic field. The principle on which the electric generator works is electromagnetic induction. The rotating conductor is in the presence of a uniform magnetic field; a voltage is induced that is utilized to power several appliances.

To get a direct current (DC, which does not change its direction with time), a split-ring type commutator must be used. With this arrangement, one brush is at all times in contact with the arm moving up in the field, while the other is in contact with the arm moving down

Thus a unidirectional current is produced. The generator is thus called a DC generator.

An important advantage of AC over DC is that electric power can be transmitted over long distances without much loss of energy.

When a rectangular coil of copper is rotated in a magnetic field, the direction of the induced current in the coil changes in every half rotation.

A fuse in a circuit prevents damage to the appliances and the circuit due to overloading. A fuse in a circuit prevents damage to the appliances and the circuit due to overloading. Overloading can occur when the live wire and the neutral wire come into direct contact. The use of an electric fuse prevents the electric circuit and the appliance from a possible damage by stopping the flow of unduly high electric current.

An electric motor is a rotating device that converts electrical energy to mechanical energy. Electric motor is used as an important component in electric fans, refrigerators, mixers, washing machines, computers, MP3 players etc.

The commutator and the brushes are responsible for the change in the direction of the current supplied to the conductor loop. The commutator is a device that reverses the direction of flow of current through a circuit. In electric motors, the split ring acts as a commutator. It serves the function of a switch to maintain the steady motion of the rotation armature.

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.

The value of the current supplied to the conductor loop is constant and it does not vary with time. Hence, option B is incorrect.

The magnetic poles remain static and their position are not reversed alternatively. 

A device that reverses the direction of flow of current through a circuit is called a commutator. In electric motors, the split ring acts as a commutator. It reverses the polarity of the current supplied to the conductor loop, enabling the change in the direction of the current.

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. Thus, option A is correct

A device that reverses the direction of flow of current through a circuit is called a commutator. In electric motors, the split ring acts as a commutator. Thus option B is also correct

For the commercial use an electromagnet in place of permanent magnet that makes it easy control the speed of the motor etc.

Hence all the statement made in the options are correct. Therefore, option D is the correct answer.