Electromagnetism Flashcards
(47 cards)
How would you plot magnetic field lines using a plotting compass?
You’d move the compass gradually around the edges of the bar magnet and makes marks in the places where the arrow of the compass points, then plot all the points together
Give four examples of magnetic materials.
Iron
Steel
Nickel
Cobalt
What rule is used to know which way the magnetic field travels around a current carrying wire?
Right hand thumb rule
Which way does a magnetic field travel in a bar magnet?
North to south
What is a permanent magnet?
A magnet that produces its own magnetic field
What is an induced magnet?
A magnetic material that becomes a magnet when put into a magnetic field
What two things make the magnetic field around a current carrying wire stronger?
A shorter distance from the wire
A higher current carried
What is an electromagnet?
A magnet whose magnetic field can be switched on or off using an electric current
What is a solenoid?
A coil of wire
Why does having more coils in an electromagnet make it stronger?
The field lines around each loop line up with each other so there will be lots of them, all close together
Give one example of a use of an electromagnet.
Cranes
Switches in circuits
What is the motor effect?
The act of movement being created by a current carrying wire being placed in between two magnets
True or false?
For the motor effect, the wire should be at 90 degrees to a magnetic field to experience full force
True
What will happen in the motor effect if the wire runs parallel to the magnetic field?
There will be no force/movement at all
What is magnetic flux density?
The amount of field lines that there are in a region
i.e. The strength of the magnet
How do you find the direction of the force which has the motor effect?
Fleming’s left hand rule
How does Fleming’s left hand rule work?
- Point your first finger in the direction of the field
- Point your second finger in the direction of the current
- Your thumb will then point in the direction of the force
How do electric motors use the motor effect?
The current carrying wire between the two magnets cause a force to be exerted, and (use Fleming’s left hand rule) one will be up and one will be down meaning the movement created is a rotation
How does a motor continue to spin using the motor effect rather than swap back and forth?
It has a split ring commutator to swap the direction of the current every half turn and therefore swap the direction of the forces.
Define the term generator effect.
The induction of a potential difference (and current if there’s a complete circuit) in a wire which is experiencing a change in magnetic field
True or false?
The force between a permanent magnet and an induced magnet is always attractive
True
Give some ways on how you might increase the strength of a solenoid.
More coils
Increase the tightness of the coils
Add an iron core
Increase the current
True or false?
In the motor effect, the strength of the force increases with the strength of the magnetic field and the amount of current passing through the conductor.
True
True or false?
The force between a permanent magnet and an induced magnet is always attractive.
True