4.6.3 - Magnetism and Electromagnetism Flashcards
(35 cards)
What are the two poles of a magnet?
- North
- South
What happens when two opposite poles are brought together?
They attract
What happens when two like poles are brought together?
They repel
Name three magnetic metals.
- Iron
- Cobalt
- Nickel
How are permanent and induced magnets different?
Permanent Magnets create its own magnetic field.
Induced Magnets only become a magnet when placed in a magnetic field.
What is a magnetic field?
An area around bar magnet where influence is felt.
Describe how to find a magnetic field using plotting compasses.
Place the plotting compass at the pole, draw an arrow to show which way the north arrow is pointing. Move the compass around the magnet and repeat. Join the arrows with lines.
Describe how to find the magnetic field using iron fillings.
Put a magnet under a piece of paper, sprinkle iron fillings on top and the shape of the field lines will be visible.
In which direction do magnetic field lines run in?
North Pole to the South Pole
How does a compass work?
Tiny magnets in the North arrow of the compass is attracted to the Earth’s magnetic South Pole.
Why does the Earth have a magnetic field?
The solid inner core moves within the liquid outer core, both made of magnetic materials - iron and nickle
The magnetism of the Earth is not static - what does that mean?
The magnetic field changes over time, it can reverse
The magnetism of the Earth is not static - what proof is there of this?
The rocks at mid-ocean ridges contain magnetic materials aligned with the previous magnetic field.
What happens when current flows through a wire?
It creates a magnetic field.
Describe the right-hand rule - how to do it and what it shows.
Point your thumb to mirror the direction of the current and do a ‘thumbs up’ whatever direction the fingers go in is the direction of the magnetic field.
Thumb - current
Fingers - direction of magnetic field
What does the strength of the magnetic field in a wire depend on?
- Current
- If the wire is straight or coiled
- If there is an iron core
What is a solenoid?
A coil of wire that can carry an electric current to create a magnetic field.
How can the strength of a solenoid be increased?
- Add a soft iron core
- Add more coils
- Make the current higher
What is an electromagnet?
A solenoid with a soft iron core.
Give an example of an object that uses electromagnetic.
- Doorbell
- Loudspeaker
State three ways we can make an electromagnet stronger.
- Increase current
- Add more coils to the solenoid
- Add a soft iron core
What are the advantages of an electromagnet over a permanent magnet?
An electromagnet can be turned on and off when desired, a permanent magnet can’t
What is the motor effect?
Current carrying wire that is perpendicular to a magnetic field, it creates a force.
What is the left-hand rule used for?
Finding out the direction of the force acting on a current, carrying wire in a magnetic field
