magnetic fields

Question 1

compare the forces between like and unlike magnetic poles

Answer 1

unlike poles attract, like poles repel

Question 2

name 4 magnetic materials

Answer 2

cobalt, steel, iron and nickel

Question 3

how does a compass work

Answer 3

a compass contains a small bar magnet (the needle) the needle lines up with the magnetic field it is in.

Question 4

explain how the behavior of a magnetic compass is related to evidence that the core of the earth must be magnetic

Answer 4

when a compass is not near a magnet the needle always points towards the earths north pole, showing that the earth generates its own magnetic field

Question 5

sketch the shape of a magnetic field around a long straight conductor (a wire)

Answer 5

thumbs up =, current is the direction of your thumb, magnetic field lines are your fingers (must get closer together closer to the wire)

Question 6

state two factors that will affect the strength of a magnetic field around a long straight conductor

Answer 6

size of current, distance from long straight conductor (wire)

Question 7

describe how to change the direction of the magnetic field around a long straight conductor

Answer 7

change the direction of the current

Question 8

state the main use of a solenoid

Answer 8

electromagnet

Question 9

what does a transformer do

Answer 9

changes the size of alternating voltage

Question 10

where in the national grid, electrical energy is transferred to high voltages then back to lower voltages

Answer 10

between the power station and transmission cables then between the transmission cables and consumers

Question 11

explain why very high voltages are used for the transmission wires

Answer 11

high voltages keep the current in the transmission wires low, to reduce heating in the wires and improve efficiency

Question 12

explain how a magnetic force arises

Answer 12

magnetic forces arise when magnetic fields interact with each other

Question 13

when a current carrying wire is placed near a magnetic, it experiences a force, recall the size and direction of the force that will act on the magnet

Answer 13

equal size, opposite direction

Question 14

Use Fleming’s left hand rule to work out the direction of the force.

Answer 14

down

Question 15

State the factors that affect the size of an induced potential difference.

Answer 15

The strength of the magnet, the number of coils, speed of the magnet.

Question 16

the factor that affects the direction of an induced potential difference

Answer 16

the direction of the movement of the pole of the magnet