GCSE Edexcel Physics 12.2 - Motor Effect (higher)
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1
What is the motor effect?
When a wire with current flowing through it is placed in a magnetic field and experiences a force
2
What happens when a current-carrying conductor (wire) is placed near a magnet?
The wire experiences a force
The magnet experiences an equal and opposite force
The magnet experiences an equal and opposite force
3
How can you increase the force exerted on a current-carrying wire in a magnetic field?
Increase the current
Increase the strength of the magnetic field
Place the wire at exactly 90 (degrees symbol) to the direction of the magnetic field
Increase the strength of the magnetic field
Place the wire at exactly 90 (degrees symbol) to the direction of the magnetic field
4
What are magnetic forces caused by?
Two magnetic fields interacting with each other
5
Why does a wire with current flowing through it experience a force when it is placed near a magnet?
The magnetic field of the magnet and the magnetic field of the wire interact
6
Fleming’s left hand rule
7
Equation for calculating magnetic force
Force (N) = Magnetic Flux Density (T) x Current (A) x Length of wire (m)
F = BIL
F = BIL
8
D.C. motor with coil in horizontal position
The split ring is touching the carbon brushes so current is flowing through the wire
The magnetic field of the wire interacts with the uniform magnetic field so the wire experiences a force
Forces act in opposite directions on each side of coil so the wire rotates (Fleming;s left hand rule)
The magnetic field of the wire interacts with the uniform magnetic field so the wire experiences a force
Forces act in opposite directions on each side of coil so the wire rotates (Fleming;s left hand rule)
9
D.C. motor with coil in vertical position
Split ring is no longer in contact with the carbon brushes
There is no current in the wire, so there is no force
The wire rotates because of the momentum it has from before
When carbon brushes and split ring reconnect, the wire experiences a force again and continues rotating in the same direction
There is no current in the wire, so there is no force
The wire rotates because of the momentum it has from before
When carbon brushes and split ring reconnect, the wire experiences a force again and continues rotating in the same direction
10
How can you increase the rotation speed of a D.C. motor?
Increase the current
Use a stronger magnet (increase strength of magnetic field)
Use a stronger magnet (increase strength of magnetic field)
11
How can you change the direction in which the coil is rotating in a D.C. motor?
Change the direction of current
Reverse the poles of the magnet
Reverse the poles of the magnet
12
How can you increase the force supplied by a D.C. motor?
Increase the current
Use a stronger magnet (increase strength of magnetic field)
Add more turns to the coil
Use a stronger magnet (increase strength of magnetic field)
Add more turns to the coil