Transformers
Lesson notes
Overview
Two coils on an iron core step AC voltage up or down in proportion to their turns. This topic is rated advanced and is number 85 of 227 in Physics. Deeper models, formal results and harder reasoning.
What you are seeing
The panel above shows a bar chart that compares values on one scale, so differences in size are easy to see. The animation is drawn live from the model, so everything you see responds to the sliders. Press Space to pause, use Restart to replay from the start, and change the speed to slow down quick events.
In depth
A transformer has two coils wound on a shared iron core. An alternating current in the primary creates a changing flux, which induces a voltage in the secondary in proportion to the number of turns: V₂/V₁ = N₂/N₁. More turns on the secondary steps the voltage up and the current down, and fewer turns does the reverse, with power roughly conserved. Transformers work only with changing currents and are central to the electrical grid.
Reading the relationship
The expression "V₂/V₁ = N₂/N₁" is a compact summary of the idea. It uses the symbols V₂, V₁, N₂, N₁; name what each one stands for before you start. Notice that it contains a ratio, so increasing the denominator makes the result smaller. Then use the sliders to see how changing one quantity changes the others.
A guided exploration
1. Run the animation once with the default settings and describe in words what happens. 2. Change one slider at a time and note which quantity responds most. 3. Push each slider to its extreme and decide whether the result still makes sense.
Try this
Try to explain why the pattern holds, not just what it is. Look for limiting cases and what happens at the edges.
Common pitfalls
Check units and directions first. Many mistakes come from mixing up a scalar with a vector, or from using a formula outside the conditions where it holds.
How it connects
It builds on “Alternating Current”, the topic before it in Physics. Once you are comfortable, continue with “Electric Motors and Generators”.
Why it matters
Physics explains how the world moves, heats, shines and interacts, and the same principles power technology around you.
Where you might use it
- Revising “Transformers” before a class, exam or certification
- Designing vehicles, bridges and devices where motion, forces or waves must be predicted
- Understanding how sensors, lasers and communication links actually work
- Explaining everyday phenomena such as sound, light, heat and orbits
Frequently asked questions
What is Transformers?
Two coils on an iron core step AC voltage up or down in proportion to their turns. It is an advanced topic in Physics.
How do I use the Transformers simulation?
The panel at the top shows a bar chart that compares values on one scale, so differences in size are easy to see. Move the sliders one at a time, then press Space to pause the animation and look closer.
What does the formula mean?
The expression V₂/V₁ = N₂/N₁ packs the idea into symbols. Name each symbol first, then change one quantity with the sliders and see which others respond.
Who is this topic for?
Deeper models, formal results and harder reasoning. If the quiz feels hard, reread the lesson notes and try the previous topic first.
What should I learn before this?
Start with “Alternating Current”, the previous topic in Physics. Each topic in a subject builds on the ones before it.
How do I track my progress?
Press “Mark as learned” on this page. Progress is stored only in this browser and is never sent anywhere. The Browse page can show topics you have learned or still need to learn.
Quick quiz
More in Physics
See all →Electric Motors and Generators
The same device run backwards: current in a field creates motion, motion in a field creates current.
Lenz’s Law
Induced currents always oppose the change that creates them — energy conservation at work.
The Photoelectric Effect
Light below a threshold frequency ejects no electrons, however bright — proof that light comes in quanta.