Topic 4

Question 1

What is energy?

Answer 1

The ability to do work

Question 2

Thermo couples

Answer 2

-Used to convert heat directly to electricity - a loop of wires made of different types of metals wrapped together at both ends or junctions - One junction is heated and one is cooled, this creates a small electric current - greater difference = greater current

Question 3

Thermo electric generators

Answer 3

Based on the thermocouple- heat moves through a thermopile( several thermo-couples connected in series)
creating a potential difference

One side of the pile is heated using a gas burner, and the other is kept cool using a radiator. This creates a steady flow of electricity of about 15-550 W. Multiple generators create up to 5000 W.

Question 4

Piezoelectric effect(electricity to motion)

Answer 4

converts electrical current into motion
- a piezoelectric crystal is connected to a potential difference, and the crystal expands or contracts slightly. Anything touching the crystal experiences pressure which can create motion, vibration or sound

Question 5

Motion to electricity

Answer 5

This is the Piezoelectric effect in reverse. When pressure builds up on one side of the crystal, it builds a voltage on the other side. Conductors connect to the crystal and con connect into a circuit.

Question 6

Electricity to light

Answer 6

Incandescent- electricity to heat to light
Fluorescent- current passes through gas to glow brightly
Led(light emitting diodes)- solid-state component that glow when electricity flows through
them.

Question 7

Light to electricity

Answer 7

Use photovoltaic cells. Made of semiconducting material and when hit by light some is absorbed and electrons are knocked loose, and allowed to move freely. Metals contacts on the tip and bottom of the cell allow this current to be used for external use.