Содержание
- 2. What do inductors do? Consider this circuit What will happen when the switch is closed? Lamp
- 3. Why? As the current starts to flow through the inductor, a magnetic field starts to form
- 4. Why? This opposing voltage restricts the current build-up in the circuit so it takes a while
- 5. Inductors Once the current has reached it’s full value, it is no longer changing, so the
- 6. Inductors The reverse happens when the current is switched off. A collapsing current will cause the
- 7. Inductance The effect of an inductor in a circuit is measured as inductance L The changing
- 8. Inductance Faraday’s Law states:
- 9. Inductance So the size of the induced back EMF depends on the inductance of the inductor
- 10. Changing Current When the switch is closed, current starts to flow in the circuit It will
- 11. Changing Current Without Inductor With Inductor
- 12. Time Constant The time constant τ is defined as the time taken for the current to
- 13. Time Constant The time constant depends on: The size of the inductor (bigger L means more
- 14. Back E.M.F The back e.m.f will be large to begin with as the current is changing
- 15. Energy Energy is stored in the magnetic field around the inductor. If the current is suddenly
- 16. Transformers These consist of 2 coils wound close to each other. Changing the current in one
- 17. Transformers The ratio of the windings determines how much voltage/current is induced The voltage can be
- 18. Transformers No transformer is 100% efficient, but assuming it was: Power in = Power out
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