Summary
Electromagnetic induction involves generating an electromotive force (e.m.f.) by changing the magnetic environment of a conductor. It is a fundamental principle behind many electrical devices.
- Electromagnetic Induction — the process of generating an e.m.f. by changing the magnetic field around a conductor. Example: Moving a magnet through a coil of wire induces an e.m.f.
- Fleming’s Left-Hand Rule — a rule to predict the direction of force on a current-carrying conductor in a magnetic field. Example: Thumb indicates motion, first finger indicates magnetic field, and second finger indicates current.
- Solenoid — a coil of wire that generates a magnetic field when an electric current passes through it. Example: A solenoid with an iron core becomes an electromagnet when current flows.
- A.C. Generator — a device that converts mechanical energy into alternating current electricity using electromagnetic induction. Example: Rotating a coil in a magnetic field induces an alternating current.
Exam Tips
Key Definitions to Remember
- Electromagnetic Induction: Generating an e.m.f. by changing the magnetic field around a conductor.
- Solenoid: A coil of wire that generates a magnetic field when current flows through it.
Common Confusions
- Confusing the direction of current with the direction of magnetic field lines.
- Misunderstanding that a transformer only works with alternating current (a.c.), not direct current (d.c.).
Typical Exam Questions
- What is electromagnetic induction? The process of generating an e.m.f. by changing the magnetic field around a conductor.
- How does a solenoid work? A solenoid generates a magnetic field when an electric current passes through it.
- How can you increase the strength of an electromagnet? Increase the number of coils, the current, or use a magnetic core.
What Examiners Usually Test
- Understanding of Fleming’s Left-Hand Rule.
- Ability to explain how electromagnetic induction works in generators and transformers.