Magnetism Don't know Flashcards
The force between a magnet and a magnetic field is…
always attractive regardless of the poles
What do poles do when they come into contact
They either attract or repel
Like poles what?
Repel
Unlike poles what?
Attract
Where do compass needles always point to? (when no magnets are interfering) Why?
The north pole because the earth has its own magnetic field showing that the Earth’s core is magnetic.
What produces a magnetic field?
An electric current. When an electric current flows it produces a magnetic field.
What is a magnetic field made of?
Concentric circles perpendicular to the wire
What is the right hand rule?
Point thumb in direction of current and curl fingers around it. This is the direction of the magnetic field.
What is a solenoid?
A coil of wire
How do you increase the strength of a magnet that a wire induces?
Wrapping the wire around a solenoid (a coil of wire). It can be strengthened further by putting a block of iron in the centre of the coil (solenoid)
Why does a solenoid increase a magnetic field?
The field lines around each loop of wire line up with each other. This causes lots of field lines in the same direction that are very close to each other and the more field line there are the stronger the magnetic field is. (p161 in revision guide)
What is the magnetic field inside a solenoid?
A strong and uniform magnet so it has the has the same strength and direction at every point in that region.
What is the magnetic field like outside a solenoid?
Just like a field around a bar magnet
What is an electromagnet?
An electromagnet whose magnetic field can be turned on and off with an electric current.
Or a solenoid with an iron core.
When are electromagnets used
Electric bells, car ignition circuit and some security doors.
