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! 🙂

  • 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. 🙂
Thats all, kiddos. 

Will test u all next lesson. 

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