Lesson 2: How Electricity is Generated?

Question 1

How does an Electric Generator work:

Answer 1

• The polarity of the electro-motive force generates a current whose magnetic field opposes the change that generates it
• When a magnet passed through the inside of a copper coil, a voltage difference was generated at the ends of the cable
• It will only happen when the magnet is in motion
• The sign of the voltage varied depending on the direction in which the magnet moved
• The wind generator rotates because the air collides with its blades and generates a torque with respect to the shaft, which generates energy
• The hydroelectric plants allow water that is in height to fall on turbines, forcing them to turn and generate energy
• Nuclear power plants produce a large amount of heat that is used to heat water which when evaporated, expands its size and being guided by the pipes, spun by a turbine
• The generators use a linear movement and the other generators have a circular motion

Question 2

Features of a Turbine

Answer 2

• Made of blades that rotate around a central haft eg wind turbine
• A liquid or gas flows through the blades to make them spin and power the turbine shaft
• Jet engines are turbines that run on kerosene
• Gas turbines burn natural gas to power ships

Question 3

What does the Faraday’s first law of electromagnetic induction state?

Answer 3

Faraday’s first law of electromagnetic induction states that a changing magnetic field will induce an electric current in a conductor.

Question 4

Consider the following statement, “A generator creates electricity.”
Is this statement accurate? Why/why not?

Answer 4

This statement is accurate because as the generator spins it produces energy which is the source for powering electricity.

Question 5

How does the portable radio recharge its batteries?

Answer 5

This portable radio uses a combination of solar cells and a hand-turned dynamo to recharge its batteries.

Question 6

How can bikes run their front lights?

Answer 6

Bikes can use hub dynamos or bottle dynamos to generate the current needed to run their front lights.

Question 7

Faraday’s Law of Induction: (rule)

Answer 7

ε = - dΦB/df

Question 8

Faraday’s Law of Induction explanation:

Answer 8

• Faraday’s law of induction tells us that the electro-motive force generated is equal to the derivative of the magnetic field with respect to time
• The e stands for electro-motive force, which is equivalent to the voltage that will be generated in the circuit
• The fb and the top stands for the magnetic field flow which refers to the direction and force of the magnetic field
• Both d’s and the f at the bottom is the derivative which is a variation in time

Question 9

Features of a Generator

Answer 9

• Central shaft, but magnets wound with wire are mounted on it
• The shaft and magnets make up the generator rotor
• Around shaft and magnets are stationary coils of wire that make up the generator stator
• When the shaft rotates, the magnets of the rotor produce magnetic fields that pass over the coils of wire in the stator, generating an electrical current in them
• The generators always have magnetic fields passing over coils of wire to produce electric current
• They generate power for the electric grid in power stations
• They produce the electricity required for lights and electric control systems