Magnetism and Electromagnetism - SS1 Physics Past Questions and Answers - page 2

A magnetic field is a region in which a magnetic force can be detected. It is created by moving electric charges or by the presence of magnets. The properties of a magnetic field include direction, strength, and magnetic field lines.

The direction of a magnetic field is indicated by the north and south poles of a magnet. The strength of the magnetic field is determined by the proximity of the magnetic source. Magnetic field lines are imaginary lines that depict the direction and strength of the magnetic field. They form closed loops around a magnet, and the density of the field lines represents the strength of the field.

When an electric current flows through a conductor, it creates a magnetic field around the conductor. This phenomenon is known as Ampere's law. The magnetic field produced is circular and perpendicular to the direction of the current. The direction of the magnetic field can be determined using the right-hand rule. If you grasp the conductor with your right hand, such that your thumb points in the direction of the current, then the curled fingers indicate the direction of the magnetic field lines.

Permanent magnets and electromagnets are two types of magnets with distinct characteristics and applications.

Similarities:

• Magnetic Field Generation: Both permanent magnets and electromagnets generate magnetic fields.

• Attraction and Repulsion: They exhibit attraction and repulsion based on their poles.

• Magnetic Properties: Both magnets can magnetise nearby magnetic materials.

Differences:

• Magnetism Generation: Permanent magnets have inherent magnetism due to their material composition, while electromagnets generate magnetism through the flow of electric current.

• Magnetism Control: The magnetism of permanent magnets cannot be easily controlled, while electromagnets can have their magnetic strength adjusted by varying the current.

• Strength: Permanent magnets generally have fixed magnetic strength, while the strength of an electromagnet can be adjusted as needed.