Transformers (GCSE Physics) - Study Mind (2024)

Efficient Energy Transfers

Transformers

  • Electrical energy transfers should be efficient. When transporting so much electricity across the country, there is a huge risk of energy waste because the power is so high. Therefore, the National Grid needs to make the transfer of electrical energy as efficient as possible. To do this, the National Grid makes use of transformers.
  • Transformers change the voltage of a circuit. Transformers used electromagnetic induction to change the voltage of a circuit – they either increase it (step-up transformers) or decrease it (step-down transformers). The National Grid has very high powers, meaning very high currents and voltages. During transport, we can boost the voltage very high and make the current very low, but still maintain the same power.
  • Step-up transformers are used at the start. As soon as electricity leaves the power station, a step-up transformer increases the voltage. As resistance is constant, current falls to a very low level (V=IR). When the current is low, we are able to reduce the energy losses via heat.
  • Step-down transformers are used at the end. When the electricity reaches the place of use, a step-down transformer decreases the voltage and thus increases the current (since resistance is constant). The electricity can now be used in homes, offices and any other domestic use. The current is high enough to give us a good energy supply.
Transformers (GCSE Physics) - Study Mind (1)

Mechanism of Transformers

Later in the section ‘Magnetism’, we will learn that a changing electric current can induce a magnetic field, and vice versa. The principle is called electromagnetic induction.

Transformers use electromagnetic induction to change the voltage of a circuit – either increase it (step-up transformers) or decrease it (step-down transformers).

Transformers (GCSE Physics) - Study Mind (2)

If an alternating current passes through a coil of wire, a changing magnetic field is produced. If you place a second coil of wire nearby, the changing magnetic field will induce a new alternating current in this second coil. This is how a transformer works,

Transformers only work for alternating current, because you need a changing magnetic field.

The size of the induced voltage depends on the number of turns on each coil – if there are less in the secondary coil, the voltage falls, and if there are more in the secondary coil, the voltage rises.

FAQs

→What is a transformer?

A transformer is an electrical device that is used to change the voltage of an AC electrical supply. It does this by using magnetic induction to transfer energy from one coil of wire to another.

→How does a transformer work?

A transformer works by using magnetic induction. When an AC voltage is applied to one coil of wire, it creates a magnetic field that induces a voltage in a second coil of wire. The voltage in the second coil is proportional to the number of turns in the coil.

→What is magnetic induction?

Magnetic induction is the process by which a magnetic field creates an electric field. In a transformer, magnetic induction is used to transfer energy from one coil to another.

→What are the different types of transformers?

There are several different types of transformers, including step-up transformers, step-down transformers, isolation transformers, and autotransformers. Each type of transformer is designed for a specific purpose, such as increasing or decreasing the voltage of an AC electrical supply.

→What is a step-up transformer?

A step-up transformer is a type of transformer that increases the voltage of an AC electrical supply. This is achieved by using more turns in the secondary coil than in the primary coil.

→What is a step-down transformer?

A step-down transformer is a type of transformer that decreases the voltage of an AC electrical supply. This is achieved by using fewer turns in the secondary coil than in the primary coil.

→What is an isolation transformer?

An isolation transformer is a type of transformer that is used to isolate two electrical circuits from each other. This is achieved by using two separate coils of wire, with no direct electrical connection between them.

→What is an autotransformer?

An autotransformer is a type of transformer that uses a single coil of wire to change the voltage of an AC electrical supply. The voltage change is achieved by tapping into the coil at different points, rather than using separate primary and secondary coils.

→What are the uses of transformers?

Transformers are used in many different applications, including power generation and distribution, electrical equipment, and electrical appliances. They are used to change the voltage of an AC electrical supply so that it can be used safely and efficiently.

→What are the advantages of using transformers?

The main advantages of using transformers include increased safety, increased efficiency, and increased reliability. Transformers allow electrical power to be transmitted over long distances without losing energy, and they also provide electrical isolation between different parts of a system.

Transformers (GCSE Physics) - Study Mind (2024)
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