7 Magnetism and Electromagnetism

Question 1

What is an alternator?

Answer 1

A device that makes use of the generator effect to generate an alternating current.

Question 2

What are current carrying wires?

Answer 2

When current flows through a wire, a magnetic field is generated around it. The strength of the field is dependant on the magnitude of the current and the distance from the wire.

Question 3

What is a dynamo?

Answer 3

A device that makes use of the generator effect to generate a direct current.

Question 4

What is an electric motor?

Answer 4

A current-carrying coil of wire in a magnetic field. The two sides of the coil that are perpendicular to the magnetic field experience forces in the opposite direction, causing rotation.

Question 5

What is an electromagnet?

Answer 5

A solenoid with an iron core.

Question 6

State the generator effect

Answer 6

When there is a relative motion between an electrical conductor and a magnetic field, a potential difference will be induced across the ends of the conductor. A current will flow if this conductor is part of a complete circuit.

Question 7

What is an induced magnet?

Answer 7

A material that becomes a magnet when placed in an existing magnetic field, but loses its magnetism quickly once removed from the magnetic field. Induced magnetism always produces attractive forces.

Question 8

What is a magnetic compass?

Answer 8

A device containing a small bar magnet that points in the direction of the earths magnetic fields.

Question 9

What are magnetic field lines?

Answer 9

Lines that represent the strength and direction of a magnetic field. The field line direction at any point is in the direction that a force would act on another north pole if placed at that point.

Question 10

What is a magnetic field?

Answer 10

The region around a magnet in which another magnet or magnetic material will experience a force.

Question 11

Which materials are magnetic?

Answer 11

Iron, Steel, Cobalt and Nickel

Question 12

What are magnetic poles?

Answer 12

The regions of a magnet where the magnetic fields are at their strongest.

Question 13

What is a microphone?

Answer 13

A device that uses the generator effect to covert the pressure variations of sound waves into variations in the electrical current of a circuit.

Question 14

What is the motor effect?

Answer 14

When a current-carrying wire is placed in a magnetic field, a force will be experienced between the wire and the magnet responsible for the field.

Question 15

What is a permanent magnet?

Answer 15

A magnet that produces its own magnetic field.

Question 16

What is a solenoid?

Answer 16

A wire wrapped in the shape of a coil, that has a strong and uniform magnetic field inside of it. The solenoid’s magnetic field strength can be increased by adding an iron core.

Question 17

What is a step-down transformer?

Answer 17

A transformer, that has a smaller potential difference in the secondary coil than in the primary coil.

Question 18

What is a step-up transformer?

Answer 18

A transformer, that has a larger potential difference in the secondary coil than the primary coil.

Question 19

What is a tesla?

Answer 19

The unit of magnetic flux density.

Question 20

What is a tramsformer?

Answer 20

An iron core with a primary and secondary coil of wire wound around opposite ends.