Magnetism - Physics

magnetism and electromagnetism

What is a magnetic material?

A magnetic material is one that will attract or repel a magnet. / An object which experiences a force when placed near a magnet.

List 3 examples of magnetic materials

Magnadur, Iron, Nickel, Cobalt, Steel (contains magnetic materials)

What two ‘poles’ are found in a magnet?

North and South OR North Seeking and South Seeking

What is magnetic induction?

Magnetic induction is the process by which magnetic properties are transferred from one object to another when a magnetic field influences the object. This leads to temporary magnetization or the creation of induced magnetic fields.

Explain what happens to the dipoles in a magnet when placed near to another magnet.

When a magnet is placed near another magnet, its dipoles realign in response to the external magnetic field, either attracting or repelling depending on the orientation of their poles.

Differentiate (using 2 characteristics) between a permanent and a temporary magnet.

Permanent magnets are able to retain their magnetism for long and are not easily magnetised, while temporary magnets do not retain their magnetism well and are easily magnetised.

Give 2 uses of a permanent magnet and 2 uses of a temporary magnet

Permanent: loudspeakers, directional compasses and refrigerator magnets. Temporary: magnetic relays, electromagnetic circuit breaker, electromagnets, electric bells

What is a magnetic field?

A magnetic field is a region in space where a magnetic material experiences a force.

What are two methods used to find the shape of a magnetic field? Briefly explain each

Iron fillings: Iron filings can be spread over a surface where a magnet is placed, allowing the filings to align along the magnetic field lines, visually indicating the field's shape.

Plotting compass: where the needle aligns itself with the magnetic field (North). Points are made as the magnet moves and it eventually points to the south pole…showing the direction of the field lines.

What creates a magnetic field around a wire?

Electric Current/Current/Movement of Charge

Explain the right hand grip rule

The right hand grip rule is a method used to determine the direction of the magnetic field around a current-carrying wire. By wrapping your right hand around the wire with your thumb pointing in the direction of the current, your fingers will curl in the direction of the magnetic field lines.

Explain how a simple D.C (Direct current) motor operates

Following Fleming’s left-hand rule, the left side of the coil experiences a downward force, causing it to rotate. After half a turn, the right side needs an upward force to keep rotating. A split-ring commutator helps by reversing the current direction every half turn, keeping the rotation continuous.

What 3 factors affect the thrust (force) in a motor

Magnitude of current, Strength of magnetic field and the number of turns in the coil influence the motor's thrust.

Explain Fleming’s Left Hand rule

Fleming's Left Hand Rule is a technique used to determine the direction of force experienced by a current-carrying conductor in a magnetic field. By aligning your thumb, index finger, and middle finger perpendicular to each other, the thumb represents the direction of force, the index finger indicates the magnetic field direction, and the middle finger shows the current direction.

What is ‘electromagnetic induction’?

Electromagnetic Induction occurs when there is a relative movement between a magnet and a conductor. This induces an electromotive force (EMF) in the conductor, generating an electric current if the circuit is closed. This phenomenon is the basis for many electrical generators and transformers.

What is Faraday’s Law?

Faraday's Law states that a change in magnetic field within a loop of wire induces an electromotive force (EMF) in the wire.

What is Lenz’s Law?

Lenz's Law states that the direction of the induced current from electromagnetic induction will oppose the change in magnetic field that produced it, thus conserving energy.