Topic 12 & 13 Magnetism, motor effect & EM induction Flashcards
1 What are the two ends of a bar magnet called?
north-seeking pole and south-seeking pole, or just north pole and south pole
2 Name two magnetic materials.
any two from iron, cobalt, nickel, steel
3 What happens if you arrange two magnets with their north poles close to each other?
They repel each other.
4 How can you arrange two magnets so they attract each other?
put opposite poles close to each other/put a north pole near a south pole
5 What is a magnetic field?
the space around a magnet which affects magnetic materials
6 How can you find the shape of a magnetic field?
use iron filings or plotting compasses
7 Name two electrical devices that use magnets.
any two from motors, loudspeakers, generators
8 Why do compasses point north?
The Earth has a magnetic field.
9 Describe the shape of the Earth?s magnetic field.
similar to the field of a bar magnet
10 Why are compass needles weighted at one end?
In most places the Earth’s magnetic field is not parallel to the surface.
11 Which part of the Earth is responsible for the Earth?s magnetic field?
outer core
12 What is the difference between the Earth?s north magnetic pole and its North Pole?
The Earth spins around an axis through the North Pole; the north magnetic pole is where compasses point to.
13 What is an induced magnet?
something that is a magnet only because it is in the magnetic field of another magnet
14 Name two materials that an induced magnet could be made from.
any two from iron, cobalt, nickel, steel
15 You are using plotting compasses to find the shape of the magnetic field of a bar magnet. Which way does the needle point?
away from the north pole/towards the south pole
16 How does a magnetic field diagram show where the field is strongest?
strongest where the lines are closest together
17 What is a uniform magnetic field?
a field with the same strength and direction everywhere
18 How can you produce a uniform magnetic field?
using two flat magnets
19 What is the shape of the magnetic field around a wire with a current flowing through it?
circular around the wire
20 What is an electromagnet?
a magnet made when current flows through a coil of wire
21 How can you create a magnetic field around a wire?
pass a current through it
22 Where is the magnetic field of a wire strongest?
close to the wire
23 How can you increase the strength of the field around a wire?
increase the current
24 How can you change the direction of the field around a wire?
change the direction of the current
25 What is a solenoid?
a coil of wire with a current flowing through it/another name for an electromagnet
26 Why is an electromagnet called a temporary magnet?
It is only magnetic when a current is flowing.
27 Describe the magnetic field inside a solenoid.
uniform, along the centre of the coil
28 Why is the magnetic field of a solenoid stronger inside the coil than outside it?
The fields from the two halves of the coil reinforce each other in the middle and partially cancel each other out outside it .
29 Describe the magnetic field between two flat magnets.
uniform, has the same strength and direction everywhere
30 What is the motor effect?
a force produced when a current flows in a magnetic field
31 How can you make a magnetic field around a wire?
pass a current through the wire
32 Where is the magnetic field of a wire strongest?
close to the wire
33 How can you increase the strength of the field around a wire?
increase the current
34 What is a solenoid?
a coil of wire with a current flowing through it/another name for an electromagnet
35 Why is an electromagnet called a temporary magnet?
it is only magnetic when a current is flowing
36 Give two ways of increasing the strength of the motor effect
increase the current, use a stronger magnetic field
37 What does Fleming?s left-hand rule help you to work out?
the direction of the force produced when a current flows in a magnetic field
38 What does magnetic flux density measure?
strength of a magnetic field
39 What are the units for magnetic flux density?
tesla, or newtons/amp metre
40 What is a transformer?
a device for changing the potential difference of an electricity supply
41 What does a transformer do?
changes the potential difference of an electricity supply
42 What are the two sets of coils in a transformer called?
primary and secondary coils
43 What are the coils in a transformer wound onto?
iron core
44 What does potential difference measure?
energy transferred by each coulomb of charge
45 What is the equation for calculating electrical power?
power = current x potential difference
46 What are the units for electrical power?
watts
47 100 W of power are transferred to a transformer via the primary coil. How much power is transferred away from the transformer?
100 W
48 What is the national grid?
the wires and transformers that send electricity around the country
49 What is a transmission line?
the wires on pylons or underground that transfer electricity
50 What is the difference between a step-up and a step-down transformer?
one increases the voltage and the other decreases it