# Losses in Transformer Short Questions Answers Physics

## Losses in Transformer

#### 1. What is an iron loss in a transformer and how it can be reduced?

In a transformer, a soft iron core is used. When a.c. current is pas through the transformer, eddy current is produced in the core and due to this will be the energy loss in the form of heat. This loss of one due to the iron core is known as iron loss. It can be reduced by laminating it.

#### 2. What is a copper loss in a transformer?

The wires of the primary and secondary coils are made of copper and have ohmic resistance. When current flows through the wires, the heat is generated. So some amount of electrical energy is lost in them for heat. This loss of energy due to the copper wire is known as copper loss.

#### 3. What is hysteresis loss in a transformer?

Due to alternating current, the magnetization and demagnetization of the iron core take place repeatedly over a complete cycle. During each le of magnetization and demagnetization, some energy is lost due to hysteresis and this amount of energy is equal to the area of the system pis loop. The energy loss due to hysteresis is called Hysteresis Loss.

#### 4. What is humming loss in a transformer?

When alternating current is passed through a transformer, the co of the transformer starts vibrating due to a change in a magnetic field produces a humming sound. Due to the production of sound, some p.d. of the electrical energy is lost. This loss of energy is known as humming loss in the transformer.

#### 5. What is flux loss in a transformer?

It is impossible to make a perfect coupling of the primary and secondary coils due to which whole of the magnetic flux produced by the primary coil never gets linked up with the secondary coil. It makes the loss of energy and this loss is known as flux loss.

#### 6. Can the use of a transformer be more economical in the transmission of a.c. to long-distance? Why?

In the transmission of a.c. to long distances, if line wire is used, the resistance of the wire will be considerable. There will be a loss of energy in the form of heat which is equal to I2R. i.e. it is proportional to the square of the current. But when we step up the a.c., it increases the voltage decreasing the value of current which decreases the loss of energy. Hence the use of the transformer can be more economical in the transmission of a.c. to long distances.

#### 8. What are the factors that reduce the efficiency of a transformer?

The efficiency of a transformer is reduced due to the following factors:

(a) Copper wires of the production of eddy current in the iron core, there will be loss of energy in the form of heat.

(b) Due to the production of eddy current in the iron core, there will be a loss of energy in the form of heat.

(c) Due to the magnetization and demagnetization of an iron core, there will be hysteresis loss which also appears in the form of heat.

(d) Due to the passage of a.c. current, the core of the transformer produces a humming sound which is also a cause of loss of energy.

#### 9. What are different power losses in a transformer? What measures do you take to minimize these losses? [HSEB 2062]

A transformer has various power losses. They are

(a) Copper loss

(b) Iron core loss

(c) Flux loss

(d) Humming loss

(e) Hysteresis loss

These power losses can be minimized by the following methods.

(a) Copper loss can be reduced by decreasing its resistance i.e. by using thick wires.

(b) Iron core loss can be reduced by laminating it.

(c) Flux loss can be reduced by coupling the primary and secondary coils perfectly as possible.

(d) Hysteresis loss can be reduced by choosing a proper material like silicon steel.

#### 11. A transformer gets heated up while in use. Why?

A transformer has various power losses. They are

(a) Copper loss

(b) Iron core loss

(c) Flux loss

(d) Humming loss

(e) Hysteresis loss

The most of the energy that is lost by a transformer is converted into heat which makes the transformer hot.

#### 12. What do you mean by a dc motor?

An electrical device that converts electrical energy into mechanical energy is called a motor. Here dc current is used to generate the mechanical energy. So it is called a dc motor.

#### 13. What is the search coil?

The search coil is a small coil of some 50 turns of fine insulated copper wire and about 1 sq. km. in the area wound over a small ebonite wooden frame. The area of cross-section of the coil is so small because the fields to be measured are usually non-uniform and also sometimes it has to be introduced into narrow gaps for the measurement of fields.

#### 14. What do you mean by electromagnetic damping?

In electricity measuring devices such as a moving coil galvanometer, the coil is wound on a metal frame. As the coil moves in the magnetic field, the eddy currents are induced in the frame. These eddy currents oppose the motion of the coil (Lenz’s law) and hence opposes the motion of the pointer attached to it. As a result, the pointer quickly attains the final position without oscillation. This kind of damping of the pointer due to the eddy currents is called eddy current damping or electromagnetic damping.