Transformers
A transformer changes the voltage of an alternating current using two coils wound around an iron core.
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Play with the controls to see the idea in action.
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A transformer changes the voltage of an alternating current using two coils wound around an iron core.
- Step-up transformers raise voltage
- Step-down transformers lower voltage
- Vs over Vp equals Ns over Np
🧠 Quick quiz
Three questions. Score 2 or more to complete the topic.
What is Transformers?
Within Physics, which covers forces, energy, waves, electricity, magnetism, light and space explained through motion and experiments, this topic explains Transformers. Physics topics explain how things move, push, heat up and carry energy, so each one here pairs a definition with a live model you can change.
Check that you can explain Transformers in your own words and give one example from everyday life. If you can do that, you have understood the core idea.
Understanding Transformers explains how the physical world behaves, from sport and transport to electricity and medicine.
Transformers in detail
A transformer changes the voltage of an alternating supply using two coils wound on a soft iron core. The alternating current in the primary coil creates a changing magnetic field in the core, which induces an alternating voltage in the secondary coil. The ratio is Vₚ/Vₛ = Nₚ/Nₛ.
A step-up transformer has more turns on the secondary and raises voltage, while a step-down transformer has fewer and lowers it. For an ideal transformer, power in equals power out, VₚIₚ = VₛIₛ. Transformers work only with AC and are used in phone chargers and across the National Grid.
How the interactive helps you understand Transformers
Watch the magnetic field in the interactive. Use any sliders or buttons it offers to change the values and see how the magnetic field responds.
Before you change anything, predict the result. Then change one value at a time and check whether your prediction was right. This is a quick way to build a correct mental model of Transformers.
Real-life uses and examples
- Use Transformers to make sense of a practical and its results.
- Answer “explain” questions by linking Transformers to a clear cause and effect.
- Predict what a ball, car or circuit will do with Transformers before you do the calculation.
Common mistakes to avoid
- Mixing up Transformers with a related quantity that has different units.
- Forgetting that some quantities, such as force or velocity, also have a direction.
- Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.
Frequently asked questions about Transformers
What is Transformers?
A transformer changes the voltage of an alternating current using two coils wound around an iron core.
What are the most important points about Transformers?
The main points are: Step-up transformers raise voltage; Step-down transformers lower voltage; Vs over Vp equals Ns over Np.
Why is Transformers useful?
Understanding Transformers explains how the physical world behaves, from sport and transport to electricity and medicine.
How can I practise Transformers?
Open the interactive at the top of this page and change the controls one at a time. Predict the result before each change, then take the three-question quiz. A score of two or more marks the topic as complete on this device.
Which topics are related to Transformers?
Related topics in Physics include Isotopes, Nuclear Fission and Fusion, Orbits and Satellites.