Chapter 6 - Electromagnets, Motors and Generators

Question 1

Magnetic fields

Answer 1

The magnetic field is the area around a magnet in which there is magnetic force. Moving electric charges can make magnetic fields.
- Permanent magnets have a magnetic field.
- The strength of a magnetic field can be represented by field lines.

Question 2

What is electromagnetism?

Answer 2

• An electric current produces a magnetic field
• Current along a wire creates a circular magnetic force, called electromagnetism

Question 3

Solenoid

Answer 3

Wire that forms a coil with electricity flowing through it strengthens the magnetic field, (strongest at the center of the coil), and its called a solenoid.

Question 4

Electromagnets

Answer 4

If an iron rod goes through the center of a coil, the magnetic field becomes stronger, this is called an electromagnet.

Question 5

Electric Motors

Answer 5

Converts electrical energy to kinetic energy. A solenoid is placed on a swivel between a permanent magnet. They interact with each other (attraction/repulsion) causes it to spin.
- Used to spin wheels, or fans

Question 6

Generators

Answer 6

Uses kinetic energy to produce electrical energy. This is done by manually spinning the magnet or solenoid.
- Turbines use water as a spinning force.

Question 7

Turbines

Answer 7

Turbines need to be spun at high speeds.
Large generators spin their magnets, keeping their solenoids fixed.

Question 8

Turbines - Water

Answer 8

Turbines can be spun through:
- Waves (swelling movement)
-Tide
-Or flowing water (Hydro-electricity)

Question 9

Turbines - Steam

Answer 9

Most power plants act like large gas kettles, water is heated and is turned into high pressure steam that turns the turbine, while exiting the cooling towers.
Water can be heated through:
- Burning fossil fuels and organic matter
- Geothermal energy
- nuclear and solar power

Question 10

Generators - Dynamos

Answer 10

Dynamo is a device that converts mechanical energy into electrical energy.

Small magnets are spun around a solenoid, can power lights of bicycles.

Question 11

AC/DC (alternating/direct)

Answer 11

Direct - Batteries and solar cells
Alternating - Generators, dynamos and turbines (electricity in AC changes direction 50 times a second)

Question 12

Transmission of Energy

Answer 12

Power plants produce electricity of 20,000V, but will be wasted once they reach houses as the wires are long. So they use a transformer to increase it to 50,000v, and at the end they reduce it to 240v