Section 6 - Magnetism and Electromagnetism P1 Flashcards
What two poles do all magnets have?
A north and south
Define magnetic field:
It’s a region where magnetic materials experience a force
What are the metals that are magnetic materials?
- iron
- steel
- nickel
- cobalt
What are magnetic field lines used to show?
Show the size and direction of magnetic fields
-ALWAYS POINT FROM NORTH TO SOUTH
What does placing the north and south poles of two bar magnets near each other create?
-creates a uniform field between the two magnets
Describe a practical for how magnetic field lines can be seen using compasses:
- compasses and iron fillings align themselves with magnetic fields
- can use multiple compasses to see the field lines coming out of two bar magnets
- could use iron fillings on a piece of paper with a magnet below and you can see the field lines
What do magnets affect?
Magnetic materials and other magnets
What do like poles do, and what do opposite poles do?
Like poles - repel
Opposite poles - attract
What are magnetic materials attracted to?
Both poles attract magnetic materials
- the material acts like a magnet when it is brought near to a magnet
- the magnetism has been induced by the original magnet
What affects induced magnetism?
distance
-the closer the magnet and magnetic material get the stronger the induced magnetism will be
What does an electric current in a conductor produce?
A magnetic field around it
What affects a magnetic field around an electric current flowing through a wire?
- larger current, stronger magnetic field
- direction of current, determines direction of magnetic field
What are the two ways magnetic materials can be described?
soft - if it looses its magnetism quickly
hard - if it keeps its magnetism permanently
What is an example of a soft magnetic material?
iron
What is an example of a hard magnetic material?
steel
What material is used in transformers?
iron - because for mains electricity it needs to be magnetised and demagnetised 50 times er second
How can you increase the strength of a magnetic field around a solenoid?
By adding a soft iron core
When a current-carrying wire is put between magnetic poles, what happens?
-the two magnetic fields affect one another
-the result is a force on the wire
-this causes the wire to move
THIS CALLED THE MOTOR EFFECT
What angle does a wire have to be at within two magnetic poles to experience the full force?
90° to the magnetic field will experience full force
- parallel won’t experience any force
- angles in between will feel some force
What factors determine the way that the force will affect the wire between two poles?
- the magnetic field of the magnets
- the direction of current in the wire
What factors increase the magnitude of the force that the wire will get when a current is flowing through it when it’s between two poles?
- increasing the strength of the magnetic field
- increasing the amount of current flowing through the conductor
What can you do to determine the direction at which the force acts from the motor effect?
Fleming’s left hand rule
- use your left hand
- point your first finger in the direction of the field
- point your second field in the direction of the current
- point your thumb in the direction of the force (motion)
What direction does a magnetic field go?
From north to south
What direction does current go?
From positive to negative
