Physic Exam Summary Notes

Magnetic Materials & Properties

• Magnetic materials include iron and steel. Non-magnetic metals include aluminium, copper, brass, and lead.

• Ferrous metals (like iron and steel) contain iron and are magnetic. Non-ferrous metals (like aluminium, copper, lead, brass) do not contain iron.

• A magnet attracts ferrous materials and has two poles — north and south — which always appear in pairs.

Magnetic Materials & Properties

• The north pole of a magnet can be identified using a compass (which aligns itself with Earth's magnetic field).

• Iron filings are used to visualize magnetic field lines around magnets.

​Magnetic Materials & Properties

Hard vs Soft Magnetic Materials

• Hard magnetic material: retains magnetism (e.g., steel)

• Soft magnetic material: loses magnetism easily (e.g., iron)

• Iron is a soft magnetic material (magnetizes and demagnetizes easily), while steel is a hard magnetic material (retains magnetism).

​Magnetic Materials & Properties

• Two methods to magnetise steel : Stroke with a magnet, Place in a coil with current (electromagnet)

• To demagnetize a permanent magnet, it can be hammered or placed in a coil carrying an alternating current.

Electromagnets & Transformers

• An electromagnet consists of a coil of wire (solenoid) often wrapped around a soft iron core to enhance the magnetic field.

• Steel is not ideal for electromagnet cores because it retains magnetism (makes a permanent magnet).

• Increasing Electromagnet Strength : Increase the current, Increase the number of turns in the coil, Use a soft iron core inside the coil

Electromagnets & Transformers

• Transformers change the voltage of alternating current. A step-up transformer increases voltage, while a step-down transformer decreases it.

• The primary coil is the input side; the secondary coil is the output side.

• The core of a transformer is made of soft iron, which easily magnetizes/demagnetizes.

Electromagnets & Transformers

Electromagnets & Transformers

​Electromagnetic Induction

• Moving a magnet relative to a coil of wire induces an electromotive force (e.m.f.).

• Relative motion is necessary — moving both magnet and coil together does not induce current.

• The faster the movement, the larger the induced current.

​Electromagnetic Induction

• The galvanometer shows a changing current when a magnet moves in and out of a coil — this is electromagnetic induction.

​Electrical Quantities

​Electrical Quantities

​Electrical Quantities

​Electrical Quantities

• Conventional current flows from the positive to the negative terminal.

• Electron flow is from the negative to the positive terminal.

• A battery produces e.m.f. (energy source).         

• A lamp converts electrical energy to light and is represented by a specific symbol in circuits.        

​Electricity cost Calculation