P15 (Magnetism) Flashcards
Properties of magnets
- two poles, north and south
- produce magnetic field
- non contact force
2 Types of forces in a magnet
- attraction
- repulsion
How does a compass work?
- tiny bar magnet
- north pole attracted to south pole of any other near magnet
- points in the direction the magnetic field is in
Permanent magnet
- produce their own magnetic field
Induced Magnet
- magnetic material that turns into a magnet inside a magnetic field
The right- hand rule
- do the ‘thumbs up’
- when a current flows through a wire a magnetic field is created around the wire
What determines the strength of a magnetic field
- larger current
- closer to the wire
Solenoid + increase strength
- coil of wire
- increase strength by wrapping more wires into a coil
What is an electromagnet?
- solenoid with an iron core (where magnetic field can be turned on and off through a current)
2 Uses of Electromagnets
- used for scrap yards pick up metals
- used within other circuits to act as switches
Motor effect
- current carrying wire is put between magnetic poles
– the magnetic field around the wire interacts with the magnetic field it has been placed in
– magnet on the conductor exert a force on each other so the wire moves
Describe the interaction between the magnetic field and the direction of current (motor effect)
The force acts at right angles to the magnetic field of the magnets and the direction of the current
Fleming’s left-hand rule
– First finger is the direction of the field
– second finger (to the rights) direction of the currents
- thumb is the motion (force)
How loud speakers work
– And AC current is sent for a coil of the wire
– the coil surrounds one poll of a permanent magnet and is surrounded by another pole so a current causes of force on a coil (cone moves)
- variation in current makes the cone vibrate
- pressure causes sound waves
The generator effect
– The induction of a potential difference in a wire is moving relative to a magnetic field, or experiencing a change in magnetic field