PhysicsChapter 10: Electromagnetism
Transformers
Introduction
A transformer changes the magnitude of an alternating voltage using electromagnetic induction. It normally contains: primary coil; secondary coil; * magnetic core.
Definition
How It Works
Alternating current in the primary coil creates a changing magnetic field in the core. This changing magnetic flux links the secondary coil and induces an alternating e.m.f.
Step-Up Transformer
A step-up transformer increases voltage. **Nₛ > Nₚ and ideally: Vₛ > Vₚ**
Step-Down Transformer
A step-down transformer decreases voltage. **Nₛ < Nₚ and: Vₛ < Vₚ**
Ideal Transformer
**Vₛ/Vₚ = Nₛ/Nₚ For an ideal transformer: VₚIₚ = VₛIₛ**
Why A.C. Is Required
A transformer needs changing magnetic flux. A steady d.c. supply does not continuously produce the changing flux required for normal transformer action.
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Review the key facts, formulas and checks before you move on.Transformers
Sticky Notes · Quick Revision
TRANSFORMER
A.C. only in normal operation
STEP UP
- Nₛ > Nₚ
STEP DOWN
- Nₛ < Nₚ