The ‘crosses’ and ‘dots’ represent going into the plane of the paper or out of the plane of the paper. It can represent current or magnetic field flowing into or out of the plane of the paper. It is important to know the representation in other to apply your Right Hand Grip Rule (RHGR) or Fleming’s Left Hand Rule (FLHR).
Electromagnet is like a ‘temporary magnet’. When a current flows through the solenoid, it will be magnetised. When the current is switched off, the eletromagnet loses its magnetism.
To make the electromagnet stronger,
1) Increase the number of turns in the solenoid.
2) Increase the size of the current.
3) Insert a soft iron core in the solenoid.
– iron is a soft magnetic material
– it can be magnetised easily
– it can be demagnetised easily