Chapter 9 (9.1 - 9.8) - Magnetism Flashcards
(51 cards)
What are poles of a magnet
Points of the magnet where the magnetic force originates from
What happens to like poles
What happens to unlike poles
Like poles - repel
Unlike poles - attract
Relationship between force between poles and distance
Inversely proportional. As distance decreases, force between the poles increases.
Why are metals attracted to magnets
Induced magnetism - when a magnet is nearby, the metal itself becomes a magnet with unlike poles to the original magnet. This leads to the metal being attracted.
What is a permanent magnet
eg
Keeps some of its induced magnetism even after its pulled away from the magnet
eg steel
What is a temporary magnet
eg
Loses all its induced magnetism after it is pulled away from the magnet
eg iron
2 ways to make a magnet
which is more effective
Stroke the metal with the magnet
Put the metal in a metal coil and pass a one way current through it (dc)
Current method is more effective
What are magnetic materials (definition)
mention the 2 types
Can be magnetized and is attracted to magnets
2 types:
hard
soft
What are ferromagnetics
Strongly magnetic materials
Explain what hard magnetic materials are
eg and use case(s)
Materials that are difficult to magnetize but do not readily lose their magnetism
eg: steel, alcomax
use: permanent magnets
Explain what soft magnetic materials are
eg and use case(s)
Materials that are relatively easy to magnetize but their magneitsm is temporary
eg: iron, mumetal
use: electromagnets and transformers
How to demagnetize a mateiral
Hammer it repeatedly
heat it to a high temp
Pull out of a coil with AC current flowing thru it
What is the magnetic field
Region around the magnet that exerts a force on the magnetic materials in it
What is the neutral point
Point between 2 like poles where the field lines exactly cancel eachother out and the magnetic force is 0
What happens to the magnetic field lines if two poles are placed near each other
Magnetic fields combine with each other to produce a single field.
What happens when a current is passed through a wire
A weak magnetic field is produced
Properties of magnetic field when current is passed through a wire
Magnetic field lines are circled
Field lines are strongest closet to the wire
Increasing the current would increase the strength of the field
What is the rule for finding field direction when a current is passed through a wire
what shows what
Right-hand thumb rule.
Thumb points in the direction of the conventional current
Fingers point in the same direction as field lines
What is a solenoid
A long coil
Magnetic field produced in a single coil vs solenoid (properties)
Magnetic field is strong in solenoid since there are more coils
Increasing the current would increase the magnetic field produced
Same field lines as a bar magnet
Components of an electromagnet
A coil (usually copper)
A core (usually iron)
Why does an electro magnet work
When current is passed through a coil, a weak magnetic field is generated. This magnetisezes the core (induced) which creates a much more powerful magnetic field than jus the coil alone
How to increase strength of magnetic field
Increasing current
Increasing number turns in coil
Why is a force generated when a current is passed through a wire which is in an electric field
what rule is used to find the direction of the force
acronym
The current produces its own magnetic field which acts upon the poles of the magnet, generating a force.
Fleming’s Left hand rule
FBI (force, direction of magnetic field, direction of current)
