Physics - The Motor Effect

Question 1

What happens when a wire carrying a current is placed in a magnetic field?

Answer 1

It can experience a force, this is called the motor effect

Question 2

What direction does the force occur?

Answer 2

Can be changed by the direction of the current or of the magnetic field.
Fleming's left hand rule:
Thumb - motion
First finger - magnetic field 
Middle finger - current

Question 3

Factors affecting the strength if the force of the motor effect

Answer 3

• Current though the wire
• Length of the wire in magnetic field
• Magnetic field strength
• Angle of current in wire to magnetic field

Question 4

What is the equation for the force of the motor effect?

Answer 4

When the magnetic field is perpendicular to the current flowing the the wire F = BIL
Force (newtons)
B is flux density, a measurement of the strength of the magnetic field, measured in Tesla
I is current through the wire
L is length of the wire in the magnetic field

Question 5

How is a DC motor structured?

Answer 5

There is first a series with a direct current power supply, this is then connected to a split ring commutator, wire brushes within the split ring connect to each side of a wire coil that is able to rotate, this coil is placed within a magnetic field

Question 6

What is a split ring commutator?

Answer 6

A split ring commutator allows for the coil of the dc motor to rotate, it means that the wires dont get tangle but, it also means that the current is always flowing in the same direction in the coil, so the motor will spin in a full circle rather than half circles

Question 7

What can increase the speed if a DC motor?

Answer 7

An increase of either magnetic field, increasing the magnetic field in the wire means you must increase the current

Question 8

Application of electromagnets

Answer 8

• Motors and generators
• Transformers
• Speakers and headphones
• Used as magnets in scrap yards to pick up metal