Which part of a magnet are magnetic forces strongest?
The poles
1 of 21
What happens when two like poles of magnets are brought in proximity with each other?
A repulsive non-contact force is exerted
2 of 21
What happens when two opposite poles of magnets are brought in proximity with each other?
An attractive non-contact force is exerted
3 of 21
What is a magnetic field?
The region surrounding a magnet where another magnet or magnetic material experiences a non-contact force.
4 of 21
What is the difference between a permanent magnet and an induced magnet?
- Permanent magnets produces their own magnetic field all the time
- Induced magnets become magnetic when placed in a magnetic field (which only causes an attractive force and loses its magnetism when removed from the magnetic field)
5 of 21
1) What does magnetically hard?
2) What does magnetically soft mean?
1) Induced magnets which - when placed outside of a permanent magnet's field - loses its own magnetism slowly
2) Induced magnets which lose their magnetism quickly
6 of 21
What 4 materials are magnetic?
1) Iron
2) Steel
3) Cobalt
4) Nickel
7 of 21
Magnetic field line facts:
1) How do field lines show where the strongest point in the magnetic field is?
2) Do field lines cross?
1) The point where there is a high concentration of field lines
2) They never cross, touch or overlap
8 of 21
How do compasses work?
They contain a tiny bar magnet which lines up with the field lines of whichever magnetic field it is placed in. They point towards the south pole.
9 of 21
How do we use plotting compasses to map out a magnetic field?
- Place a compass on a piece of paper near the field
- Draw an arrow in the direction where the compass points
- Repeat at different points on the paper
- Join the arrows to make a complete field pattern
10 of 21
What is produced when current flows through a long straight conductor?
A magnetic field is produced around the wire
11 of 21
What determines the magnetic field strength around a current-carrying wire?
1) The magnitude of the current flowing through the wire
2) The distance from the conducting wire
12 of 21
What is a solenoid?
A coil of wire which creates a strong and uniform magnetic field along the centre of the solenoid due to the fields from the individual coils add together when current passes through it. However, the field outside of the solenoid is weak because the field
13 of 21
What is an electromagnet?
A solenoid with an iron core which increases the strength of the magnetic field
14 of 21
Magnetic forces occur because of...
… interactions between magnetic fields
15 of 21
What is the motor effect?
A force exerted which is equal and opposite between a magnet and a current-carrying conductor placed in that magnet's field.
The wire cannot be parallel to the magnet's field otherwise no force is exerted
The full force occurs perpendicular to the magnet
16 of 21
What factors affect the magnitude of the force on a current-carrying wire in a magnetic field?
1) The magnitude of current flowing through the wire
2) The strength of the magnetic field the wire is in
17 of 21
What does each finger represent in Fleming's Left Hand Rule?
1) The thumb points towards the direction of force experienced by the wire
2) The index finger points towards the magnetic field direction (north to south)
3) The middle finger points towards direction of the current
18 of 21
How do you calculate the strength of the force caused by the motor effect?
As long as the current is perpendicular to the magnetic field:
F(N) = B (T) x I (A) x l (m)
19 of 21
How does an electric motor work?
- A coil of current-carrying wire is placed in a magnetic field
- The two forces on the sides perpendicular to the field experiences forces in opposite directions
- This causes a rotational effect
*However the rotation only turns 180 clockwise then 180 a
20 of 21
How do we get an electric motor to rotate 360?
- A split ring commutator is used which swaps the positive and negative terminal every half turn
- This causes the force acting on the coil to be acting in the same direction
21 of 21
Other cards in this set
Card 2
Front
What happens when two like poles of magnets are brought in proximity with each other?
Back
A repulsive non-contact force is exerted
Card 3
Front
What happens when two opposite poles of magnets are brought in proximity with each other?
Back
Card 4
Front
What is a magnetic field?
Back
Card 5
Front
What is the difference between a permanent magnet and an induced magnet?
Comments
No comments have yet been made