magneticism Flashcards
Magnets have how many poles
north and south
Law of magnetism: Opposite poles…
attract
Law of magnetism: Like poles
repel
Magnetic materials: Uses and things
- Can be soft/hard
- Magnetically soft materials are easy to magnetise
- Easily lose their magnetism.
- Magneticcally hard:
- Difficult to magnetise
- Don’t easily lose their magnetisim.
How are permanent magnets made
Magnetically hard materials
Electromagnets are made
out of magnetically soft materials
What are magnetic fields
- Region around a magnet where force acts on another magnet/ magnetic material
Magnetic field lines: what do they represent
- Strength and direction of magnetic field
- Direction of magnetic field using arrows
- Strength of magnetic field
Strength of field lines
- If close together then field will be strong
- if far apart then field will be weak
Rules for field lines
- Always go from North to south
- Should never touch/ cross other field lines
Magnetic field around Bar magnet
- Magnetic field is strongest at the poles
- Field lines are closest together
-Field becomes weaker as distance from magnet increases - Magnetic field lines are getting further apart
Uniform magnetic meaning
- Uniform magnetic field will be produced in the gaps between opposite poles
- Outside gap… field will not be unfiorm.
Uniform magnetic field
- Has the same strength and direction at all points
- The magnetic field lines are same distance apart between gaps of poles.
How can field lines be determined
- By plotting compasses pointing from north to south
- Using iron fillings
Metals in periodic table that are magnetic
- Iron
- Cobalt
- Nickel
Magnetic materials rule
Always be attracted to magnet regardless of which pole is held close
Two types of magnets
-permanent
-induced
How to tell if material is a magnet
- It should be brought close to known magnet
- Should repel
- If only attracted and not repelled then it is a magnetic material
Difference between permanent and induced
- Permanent magnet produces its own magnetic field
Induced magnets
- Magnetic material placed din magnetic field, material can temporarily be turned into magnet
- Called induced magnetism
When magnetic material is removed from field
- It will lose most of magnetism quickly
Investigating Magnetic Fields. Compasses
- Magnet on paper
Place plotting compass next to corner of
