Magnets Flashcards
(22 cards)
Can magnetic fields travel through solid objects?
Yes
What happens to the magnetic field lines when unlike poles come together?
They converge because unlike poles attract
What happens to the magnetic field lines when like poles come together?
They diverge because like poles repel
What is an electromagnet?
When a current flows through a coil of wire, a magnetic field is produced around the coil. This is an electromagnet.
What factors increase the magnetic field strength of an electromagnet?
The coil is wrapped around iron, there are more coils, the voltage is increased
What is a motor?
A device that converts electrical energy into kinetic energy
What do you need to create a motor?
Electricity and a magnet
In Flemings Left Hand Rule, what is the Thumb?
direction of a force/Thrust
In Flemings Left Hand Rule, what is the First Finger?
direction of the magnetic Field
In Flemings Left Hand Rule, what is the seCond finger?
direction of the Current
What things do you need to create movement, or the motor effect?
a current in a wire with a magnetic field
What is the motor effect?
When an electromagnet is near a magnet, it feels a force and the wire moves
When is there no motor effect of an electromagnet?
If the current is parallel to the magnetic field
What increases the size of the motor effect?
Increasing the current, using a stronger magnet
What happens in an electric motor?
The motor effect is used to spin a coil of wire
What makes the motor turn faster in an electric motor?
The magnetic field or the current increasing
What makes the direction of the motor effect change in an electric motor?
The current direction changes, the magnetic field direction changes
What is electromagnetic induction?
When a wire in a complete circuit moves across a magnetic field, a voltage is induced across the wire so a current flows in the circuit.
For electromagnetic induction to take place, one of two things must move, what are they?
The magnet or the wire
In electromagnetic induction, what increases the current?
The magnetic field is stronger, the magnet/coil moves faster, there are more turns on the coil or the coil has a larger diameter.
To create electromagnetic induction, what must the coil cut through?
The magnetic field lines
How does an electric doorbell work?
1) When the switch is closed, a current flows in the circuit and the electromagnet produces a magnetic field around itself
2) This attracts the metal arm which hits the gong and breaks the circuit
3) The electromagnet loses its magnetism and the metal arm springs back. When the contacts touch, the circuit is complete again. The cycle repeats continuously until the switch is opened.
