10 Electromagnetism And Motor Effect

Question 1

Electric current in a conductor produces

Answer 1

A magnetic field around it

Question 2

Construction of electromagnetics

Answer 2

Current in coil produces a magnetic field
The iron core picks up the magnetic field
If a coil cuts a magnetic field it will induce a voltage which produces a current

Question 3

How does an alternating current in the primary coil produce an alternating magnetic field

Answer 3

Iron core picks up a magnetic field
The secondary coil cuts the magnetic field
Inducing an alternating voltage
Which produces an alternating current

Question 4

When a current flows through a conducting wire

Answer 4

A magnetic field is produced

Question 5

Right hand thumb rule

Answer 5

Used to work out direction of magnetic field
- thumb points in direction of current, other fingers give direction of field

Question 6

Larger current

Answer 6

Produces a larger magnetic field

Question 7

Greater distance from conductor

Answer 7

Weaker magnetic field

Question 8

There is a force on a charged particle when

Answer 8

It moves in a magnetic field
As long as its motion is not parallel to the field

Question 9

Motor effect occurs when

Answer 9

A wire with current flowing through it is placed in a magnetic field and experiences a force
Result of two interacting magnetic fields

Question 10

How do the forces acting in opposite directions on each side of the coil rotate in a motor

Answer 10

• current flowing through the coil produces a magnetic field
• the magnetic field interacts with the uniform external field so a force is exerted on the wire
• forces act in opposite directions on each side of the coil causing it to rotate
• creates a spinning motor

Question 11

Factors affecting the dc motor: the speed the coil rotates can be increased by

Answer 11

• increasing current
• increasing the strength of the magnetic field

Question 12

Factors affecting the dc motor: direction of the coil can be changed by

Answer 12

• reverse direction of current
• reverse the poles to reverse direction of magnetic field

Question 13

Factors affecting the dc motor: the force supplied by the motor can be increased by

Answer 13

• increasing current in coil
• increasing strength of magnetic field
• adding more turns to the coil

Question 14

How do loudspeakers work due to the motor effect in creating sound waves

Answer 14

Consists of a coil of wire which is wrapped around a permanent magnet
- alternating current passes through coil of loudspeaker which creates a changing magnetic field
- magnetic field is constantly changing as current is constantly changing
- magnetic field produced around coil interacts with field from the permanent magnet
- interacting magnetic field will exert a force on coil
- coil oscillates, makes air oscillate
- creates sound waves

Question 15

Size of force exerted by magnetic fields can be increased by

Answer 15

• increasing amount of current flowing through the wire -> increases magnetic field around it
• using stronger magnets -> increases magnetic field

Question 16

Factors affecting the magnetic field strength of a solenoid

Answer 16

• increasing size of current flowing through wire
• increasing number of coils
• adding an iron core -> becomes induced magnet

Question 17

If you increase the magnitude of current through a wire or the size of magnet used

Answer 17

You increase the force on the wire