MAGNETISM AND MAGNETIC FORCES

Magnetism

What is the property of attracting objects made of iron, nickel, and cobalt?

Magnetic Fields

The region around a magnet where a force acts on another magnet or magnetic material.

attract

The Rules of Magnetism state that opposite magnetic poles __________ each other, while like magnetic poles repel each other.

Magnetic Forces

These are non-contact forces–this means that magnets affect each other without touching.

Iron, steel, nickel and cobalt

Give one example of a magnetic material.

Permanent Magnets

Magnets made from materials like iron that always produce a magnetic field.

Key features of a permanent magnet

These include its ability to generate a magnetic field without the need for an external power source, and its capacity to retain its magnetism over a long period of time.

Induced Magnets

Materials that become magnets only when placed in a magnetic field and lose magnetism when removed.

Magnetic

Testing for magnetism involves using a compass to detect the presence of a magnetic field. If the compass needle aligns with the direction of the magnetic field, the object is considered to be _________.

Magnetic Field

It is the region around a magnet where a force acts on another magnet or on a magnetic material.

Magnetic Compass

A tool with a bar magnet that aligns with Earth's magnetic field or a magnet's field.

Solenoid

This consists of a wire coiled up into a spiral shape.

Motor Effect

Interaction between a wire carrying current and a magnetic field, causing a force on the wire.

Motor Effect

The ___________ is the phenomenon where a current-carrying conductor in a magnetic field experiences a force perpendicular to both the field and the current direction.

Fleming’s Left-hand Rule

Rule to determine the direction of the force on a wire in a magnetic field.

Force on a conductor (at right angles to a magnetic field) carrying a current = magnetic flux density × current × length

The equation for calculating electric force.

Electric Motors

A coil of wire carrying a current in a magnetic field experiences a force that tends to make it rotate.

AC Motor

A(n) __________ is an electric motor that operates on alternating current, changing direction periodically to produce rotational motion.

DC Motor

A device that converts electrical energy into mechanical energy through the interaction of a magnetic field and electric current.

Loudspeakers

In these devices, variations in an electric current cause variations in the magnetic field produced by an electromagnet. This causes a cone to move, which creates pressure variations in the air and forms sound waves.

Electromagnetic Induction

Creation of a potential difference in a conductor due to movement in a magnetic field.

Electric Potential

Potential Difference is the difference in __________ between two points in an electric circuit, representing the energy transferred per unit charge.

Magnetic Flux

Factors affecting the induced potential include the rate of change of ____, the number of turns in the coil, and the strength of the magnetic field.

Electromagnetic Induction

A potential difference can be induced (created) in a conductor when there is movement between the conductor and a magnetic field.

Alternators

Devices producing alternating current by rotating a coil in a magnetic field.

Dynamos

Devices generating direct current by rotating a coil in a magnetic field with a split ring commutator.

Half

In a dynamo, a split ring commutator changes the coil connections every ____ turn.

Microphone

A device that converts sound waves into electrical signals.

Transformers

Devices changing the potential difference of alternating current using two coils and an iron core.

Step-up transformer

A transformer where the potential difference in the secondary coil is higher than in the primary coil.

Step-down transformer

A transformer where the potential difference in the primary coil is higher than in the secondary coil.