# Magnetism and Elestromagnetism

Important notes and tips i want my sec 4 physics students to remember on this topic. Yes, you read it correctly. REMEMBER the following points! ðŸ™‚

• A freely suspending magnet comes to rest with its N pole pointing North.
• Solenoid is a long coil of insulated wire.
• One way of demagnetism is to insert a magnet into a solenoid connected to a a.c. supply. Slowly withdraw the magnet while the current is switched on.
• A magnetic field is the region around the magnet where other magnetic materials experience a force.

A compass will always point in the same direction of the magnetic field lines. Hence, the pointer of the compass arrow will ALWAYS point away from north pole towards South pole.

• Temporary magnets examples: circuit breaker, electric bells
• Permanent magnet examples examples: compasses, magnetic door catches
• When a magnet is brought near a magnetic substance, the magnetic substance becomes a induced magnet with the end nearer to the magnet having a opposite pole to the magnet. Then attraction occurs.

• Magnetic material will concentrate the field lines but non magnetic material will not.

• Summary for Right Hand Grip Rule

Straight wire: Thumb points to current, finger to magnetic field

Solenoid: Thumb points to magnetic field/ north pole. Fingers to current.

• Fleming’s left hand rule is used for determining the direction of the force on a current-carrying conductor.

Memory help:

Current starts with C. (Third alphabet in ABC) –> Third finger.

Thumb is the first finger hence imagine its most powerful. So it points to the Force. ðŸ™‚
Thats all, kiddos.

Will test u all next lesson.