Transformers
Transformers change AC voltage using coils.
About this topic
A transformer changes AC voltage using two coils wound on a shared iron core. Alternating current in the primary creates a changing flux that induces a voltage in the secondary, with Vₛ/Vₚ = Nₛ/Nₚ. A step-up transformer has more secondary turns, a step-down fewer.
Ideally power is conserved, VₚIₚ = VₛIₛ, so higher voltage means lower current. For example, 100 primary turns and 1000 secondary turns turn 230 V into 2300 V, but the current falls to a tenth. Power grids step voltage up to hundreds of kilovolts to cut I²R losses, then down for homes.
Phone chargers and laptop adapters contain small transformers or electronic equivalents, and the big grey cans on poles step the voltage down to household level. Real transformers lose a little energy as heat and in the core, with efficiencies often above 95 percent.
Transformers only work with AC, because a steady current gives a constant flux and no induced voltage. They do not create energy: a step-up transformer gives more voltage but less current.
Key ideas
- Vₛ/Vₚ = Nₛ/Nₚ
- Step-up and step-down
- Needed for power grids
Quick check
Use cases: where Transformers helps
- Homework: review the key idea behind Transformers before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Transformers without notes.
- Visual learning: play with the interactive lab to see how Transformers changes when you adjust its inputs.
- Teaching a friend: explain Transformers in your own words, then compare your version with the key ideas.
The same laws describe car crashes, sports, satellites and everyday machines.
Frequently asked questions
What is Transformers?
Transformers change AC voltage using coils.
What will I learn in Transformers?
Vₛ/Vₚ = Nₛ/Nₚ. Step-up and step-down. Needed for power grids.
Is Transformers part of Physics?
Yes. It is one of 150 Physics topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Transformers lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Transformers?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.