Simple Phenomeon Magnetism

Soft magnetic material

Easy to magnetize and demagnetize. Loses its magnetism

Hard magnetic material

Hard to magnetize and demagnetize. Keeps its magnetism

Magnetic field

Region where magnets experience a force

Magnetic field lines

Field lines

Force a north pole experiences

How are field line different when the force is weak and strong

Strong when field lines are close, weak when they are far

How to draw magnetic field line using a compass

Put magnet on sheet of paper

Put compass around the magnet and check the direction of the needle

Mark point where compass needle point on paper

Draw line through the points the magnet was pointing and you will get the magnetic field line

Repeat several times at different points around the magnet until you can draw the entire field

Which kind of magnetic field does current produce

Circles perpendicular to the direction of the current

Right hand grip rule for current in single line

Point thumb in direction of the conventional flow of the current the direction your other fingers point is the direction of the magnetic field circles that the current produces

Solenoid

Coiled wire with a current running through.

Solenoid magnetic field

Produced magnetic field similar to bar magnet but has field lines withing the solenoid

How to find direction of poles using coil of solenoid

Use right hand grip, make your fingers point the direction of the coil from in which the current comes in from, you’re thumb will be the direction of north

How to increase magnetic field of a solenoid

Increase number of turns in coil

Use iron core

Increase current/ voltage

Uses of electro magents

Relay

Speaker

How do relay work?

Solenoid used connected to one circuit, if it is switched on then it turns the switch on another circuit on, by attracting it completing its circuit

How do speaker work?

Electro magnet used connected to ac current to attract and repel the cones due to changing poles