Jan 2017

Features of an A.C Transformer

January 16, 2017


Are you up to speed on the physics of A.C transformers? If you’re looking to ace your JC physics tuition, here’s what you need most to remember about AC transformers.

What makes a transformer?

If the voltage of an input alternating current changed, but the frequency of the supply remains unchanged, you are dealing with an A.C transformer. It combines magnetism with electrical fields when a wire with running electricity generates a magnetic field.

A transformer is wire-wrapped on one side carrying AC current, and on the other a different amount of wire designed to carry current that has transformed with common shapes being rings and squares.

Wrapping it around iron increases this magnetic field exponentially. The higher the subsequent voltage [flowing current], the stronger your magnet will be. The number of turns of wire around the core iron will also make the magnet stronger. The direction of current will affect the polarity of the magnet and will reverse if the flow is reversed. If you move a wire through a magnetic field or the field past the wire, you make electricity. Make sure you’re comfortable with the concepts in electromagnets, as they’re very important to learning the physics tuition syllabus.

How do you transform voltage?

The strength of the magnetic field relates directly to the input voltage proportional to the number of turns on that primary coil. Using this fact, we can set the secondary coil up to ensure that we transform the input voltage to the desired one.

We write this relationship as:

INPUT Volt/Turns = OUTPUT Volt/Turns

A classic example is  110V in on 5 turns…you will get 220V out on 10 turns.

Remember that AC current changes direction is a critical part because DC current does not change the magnetic field in the same way. DC transformers do exist, but AC transformer has long been the standard worldwide because of its adaptability.

What do we use transformers for?

Transformers are often used in applications where battery power is used. It can assist in transforming household current to battery voltage. They can also be used to transform AC to DC power. If you’ve ever noticed your adapters getting warm, it’s because this process leads to some of the converted AC power being lost as heat.

We also have transformers within the homes as large power lines rely on very high voltage to transfer the electricity effectively over long distances. This would be incredibly dangerous within the domestic house, therefore AC transformers are used to bring it down to the safe household standard.

The AC electromagnetism principles that go into AC transformers are deceptively simple but amazingly powerful. Without them, a host of our daily electricity applications would not be possible. This subject neatly highlights how important physics can be in the ‘real’ world and the many different ways in which solid knowledge of physics help make the world a better place.

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