Level 4 · Science S4.13
Magnets, motors and generators
Electric currents and magnets push on each other, and that is how motors and generators work.
Planned. This book is not written yet. Below is its plan, which a teacher can already use.
You are ready for this book if
You can explain how to make an electromagnet stronger.
- One step up S5.14 Electric circuits and capacitors
- This book S4.13 Magnets, motors and generators
- One step down S3.10 Electricity and magnetism
The plan
- S4.13.1 Magnetic fields
- Draw field lines around a bar magnet and between two poles
- Explain the difference between permanent and induced magnets
- S4.13.2 Fields around wires and coils
- Use the right hand grip rule to find the direction of a field
- Explain how a coil of wire makes a strong, even field
- S4.13.3 The motor effect
- Use Fleming's left hand rule to find the force on a wire
- Calculate force using F equals B times I times L
- S4.13.4 Electric motors
- Explain how a split ring keeps a motor turning one way
- Name ways to make a motor turn faster
- S4.13.5 Electromagnetic induction
- Explain why moving a magnet in a coil makes a current
- Explain what makes the induced current bigger
- S4.13.6 Generators and dynamos
- Explain how a bicycle dynamo or a power station generator works
- Compare the output of an alternator with that of a dynamo
- S4.13.7 Transformers
- Use the turns ratio to calculate output voltage
- Explain why power lines carry electricity at very high voltages
- S4.13.8 Speakers and microphones
- Explain how a loudspeaker turns current into sound
- Explain how a microphone turns sound into current
- Find the magnet and coil inside an old broken speaker
For parents and teachers
Level 4 fits learners who can already: follow a written argument. use letters for numbers. In many schools that is about 14 to 16, but start wherever the learner is.
Strand: Electricity and magnetism. Written and drawn by attnom. Free to read, print and share.