Question

How do electric transformers work?

Answer 1

Electric transformers are devices that help change the voltage of electricity from one level to another. They are used in power distribution systems to either increase (step up) or decrease (step down) voltage, making it easier to transport electricity over long distances or to power specific devices. Here's how they work in simple terms:

Basic Working Principle:

Transformers work based on electromagnetic induction, which is a process where a changing magnetic field creates an electric current. When electricity flows through a coil of wire, it creates a magnetic field. A transformer uses this principle to transfer electrical energy from one circuit to another.

Key Components of a Transformer:

1. Primary Coil: This is the coil where the input electrical power is fed. When an alternating current (AC) flows through it, it generates a changing magnetic field.
   

1. Secondary Coil: This coil is where the output power is taken. It is placed near the primary coil so that the magnetic field from the primary coil can induce a voltage in the secondary coil.
   

1. Core: The core is usually made of iron and provides a path for the magnetic field. It helps increase the efficiency of the transformer by concentrating the magnetic field.
   

How the Transformer Works:

1. AC Current in the Primary Coil: When an alternating current (AC) is applied to the primary coil, it creates a constantly changing magnetic field around it.
   

1. Magnetic Field Induces Voltage in the Secondary Coil: This changing magnetic field passes through the secondary coil, and by the principle of electromagnetic induction, it generates an alternating current in the secondary coil.
   

1. Voltage Change: The number of turns (loops of wire) in the primary and secondary coils determine how much the voltage is changed. If the secondary coil has more turns than the primary coil, the transformer will step up the voltage. If the secondary coil has fewer turns than the primary coil, the transformer will step down the voltage.
   

Voltage Relation:

The voltage in the transformer depends on the ratio of the number of turns in the primary coil to the number of turns in the secondary coil. This relationship is given by:

\[
\frac{V_{\text{primary}}}{V_{\text{secondary}}} = \frac{N_{\text{primary}}}{N_{\text{secondary}}}
\]

Where:

1. \( V_{\text{primary}} \) = Voltage applied to the primary coil
   

1. \( V_{\text{secondary}} \) = Voltage in the secondary coil
   

1. \( N_{\text{primary}} \) = Number of turns in the primary coil
   

1. \( N_{\text{secondary}} \) = Number of turns in the secondary coil
   

Example:

If a transformer has 100 turns in the primary coil and 200 turns in the secondary coil, the voltage will be doubled (step-up transformer).

If the primary voltage is 100 V, the secondary voltage will be:

\[
V_{\text{secondary}} = \frac{N_{\text{secondary}}}{N_{\text{primary}}} \times V_{\text{primary}} = \frac{200}{100} \times 100 = 200 \, \text{V}
\]

Why Use Transformers?

1. Efficient Power Transmission: Transformers allow power to be transmitted over long distances with less energy loss. Higher voltages reduce the current, and less current means less energy lost as heat.
   

1. Safe Voltage Levels: Transformers step down high voltage to safer levels for home appliances and industries.
   

Summary:

In short, transformers use the principle of electromagnetic induction to change the voltage levels in electrical circuits. They are vital for the efficient transmission of electrical power over long distances and for ensuring that electrical equipment gets the right voltage for safe operation.