Physics Flashcards
Magnet
A piece of material that is capable of attracting certain metals.
Name some uses of magnets
In MRI machines, food processing, inside TVs, Sound speakers and radios, headphones and loudspeakers, generators
Permanent magnets
A magnet which remains magnetic without the need for an electric current because of the internal structure of the magnet. They can be used to attract other objects e.g. paperclips made of steel
Give some examples of permanent magnets
Paper clips, bar magnet, Horse shoe magnet, Compass, Button magnet
Magnetic material
A material which is attracted by a magnet
Non-magnetic material
A material which is not attracted by a magnet
Give examples of magnetic materials
Iron ,steel, nickel ,cobalt
Give examples of non-magnetic material
Wood, cotton, paper, aluminium, tin
______ is mostly made of iron
Steel
What are strong magnets made out of nowadays?
Neodymium
How can we separate different material?
By using a strong magnet that can attract magnetic material and the non-magnetic material will be left behind
Magnetic poles
The regions of a permanent magnet where the magnetic strength is strongest
Magnetic force
The force of a magnet on another magnet or on a piece of magnetic material
What are the magnet rules?
Like poles repel and unlike poles attract
How can we magnetise a magnetic material?
- Lay it on the bench
- Using one pole of the magnet, stroke it from one end to the other.
- Stroke it several times, using the same pole.
- Make sure you always stroke it in the same direction
Where will the north and south pole of a magnet turn?
The north pole of a magnet will turn to point north and the south pole of a magnet will turn to point south
When to unlike poles attract what does that mean?
It can be a magnet or a magnetic material
When to like poles repel what does that mean?
They are permanent magnets
Magnetic field
A region where there is a force on a magnet or a piece of magnetic material
What will happen when a magnetic material is placed in the field of a magnet?
It will be attracted by the magnet
How can we show the shape of a magnetic field?
- By using iron fillings to form a line
- Using plotting compasses to show the direction of the field
How can we represent a magnetic field?
By drawing magnetic field lines
What do magnetic fields show?
- They go from north to south
- The arrows show the direction of the field
- Where the lines are closest together is where the field is the strongest
Why do people use a compass?
Because the Earth has a magnetic field that can help us find our way around
Where will a compass needle point towards?
Earth’s magnetic north pole which is near to the geographical north pole
Electromagnet
A coil of wire with an electric current in it that works using electricity and it can be switched on and off
How can we construct an electromagnet?
By winding a coil and then connecting the ends of the wire to a battery or power supply
Name 2 differences between an electromagnet and a permanent magnet
- An electromagnet uses electricity but a permanent magnet doesn’t
- An electromagnet can be switched on and off, while a permanent magnet can’t.
Why can we switch an electromagnet on and off?
Because it’s easy to switch electricity
How can we make an improved electromagnet?
We can wrap the wire around a magnetic material (e.g iron) called a core so that when the iron becomes magnetised and this makes the magnetic field of the electromagnet stronger
Core
A piece of iron inside the coil of an electromagnet to make it stronger
Name 3 uses of an electromagnet
- For carrying heavy scarp cars
- In electric motors and generations
- In doorbells and in electric switches called relays
How can we make an electromagnet stronger?
- Make a coil with more turns of wire
- Make a bigger electric current flow in the coil of wire by connecting 2 batteries end-to-end
Ammeter
A meter used for measuring electric current
Amps
The unit in which electric current is measured, symbol A
How is the field of an electromagnet like the field of a bar magnet?
- The magnetic field lines come out of one end of the electromagnet (the north pole)
- The field lines go round and back into the other end electromagnet (the south pole)
What makes the magnetic field in an electromagnet?
The current makes the magnetic field
Who is Hans Christian Oersted?
A Danish scientist who thought that there might be a connection between electricity and magnetism in 1820
What happened in 1820?
Hans gave a lecture about electric circuits and a compass was nearby. When he switched on the circuit, he noticed the compass needle change directions
How does an electromagnet work in terms of it’s magnetic field?
The magnetic field around an wire is weak so when we wind the wore into a coil you concentrate the magnetic field into a smaller space making it much stronger
What shape are the magnetic fields in an electric current?
Circle
Where is the magnetic field the strongest in an electric current?
The field is strongest close to the wire
