Permanent & Induced Magnets Flashcards
All 6 cards in this deck
What is an induced magnet?
A magnetic material that becomes a magnet only while it is placed in (or near) a magnetic field, and loses its magnetism when the field is removed.
True or false? An induced magnet can repel a permanent magnet.
False. The force between an induced magnet and the magnet inducing it is always attraction.
Which of iron and steel is used for permanent magnets and which for temporary magnets, and why?
Steel for permanent magnets (it keeps its magnetism); iron for temporary magnets (it is easily magnetised but loses its magnetism quickly).
What are the steps of an experiment to show that iron becomes a temporary induced magnet?
e.g. using a bar magnet, an iron bar and paper clips
- Place the iron bar in contact with (or near) the magnet.
- Paper clips are attracted to the iron, and the first clip can pick up another.
- Remove the magnet — the clips are no longer attracted and fall off, so the magnetism was temporary.
What is a permanent magnet?
A magnet that always has its own magnetic field, whether or not it is near another magnet or magnetic field.
Give one use of a temporary (induced) magnet.
The soft iron core of an electromagnet, e.g. in an electric door lock: the iron is magnetised only while current flows, so the lock can be switched on and off.