Section 5 - Electricity

Question 1

What is a diode?

Answer 1

An electrical component where current can only flow in one direction.

Question 2

What is a LDR?

Answer 2

Light dependent resistor. The resistance increases as light increases.

Question 3

What is a thermistor?

Answer 3

A resistor where its resistance decreases the hotter it gets.

Question 4

In a series circuit, is the current the same or different everywhere?

Answer 4

Same

Question 5

In a parallel circuit, is the current the sane or different everywhere?

Answer 5

Different

Question 6

How does adding a resistor in parallel reduce the total resistance of a circuit?

Answer 6

By adding another loop to the circuit, the current has more than one direction to go. This increases the total current that can flow around the circuit, An increase in current means a decrease in total resistance.

Question 7

What does a.c mean?

Answer 7

The direction of the current in constantly changing direction

Question 8

What does d.c mean?

Answer 8

The direction of the current will always stay the same.

Question 9

What is the voltage of the UK mains supply?

Answer 9

230V

Question 10

What is the brown wire called in a cable and what does it do?

Answer 10

It is the live wire and it carries the voltage

Question 11

What is the blue wire called in a cable and what does it do?

Answer 11

It is the neutral wire and it completes the circuit so the electricity can flow

Question 12

What is the green and yellow wire called in a cable and what does it do?

Answer 12

It is the earth wire and it is for safety. It carries the current away if something goes wrong.

Question 13

How does a fuse work?

Answer 13

When the current passing through a fuse goes above its rating, it causes the wires in the fuse to melt, breaking the circuit.

Question 14

In what ways are circuit breakers better than fuses?

Answer 14

Circuit breakers turn off much faster than fuses. They can also be reset, while fuses have to be replaced.

Question 15

Note: you need to know circuit symbols

Answer 15

They are found on page 71 on the CGP guide

Question 16

What is Current?

Answer 16

The flow of an electric charge around a circuit

Question 17

What is needed for a current to flow?

Answer 17

A complete circuit and a potential difference

Question 18

Why does the resistance of a component usually increase with temperature?

Answer 18

The ions have more energy, and so move around more. This makes it harder for the electrons to get through as they collide with the ions more.

Question 19

Is an ammeter put in series or parallel to a circuit?

Answer 19

Series

Question 20

Is an voltmeter put in series or parallel to a circuit?

Answer 20

Parallel

Question 21

How does a fuse work?

Answer 21

A surge in current causes the wire in the fuse to heat up and melt. This breaks the circuit and stopping the electricity from flowing.

Question 22

At what current should fuses/circuit breakers be rated at?

Answer 22

Just higher than the normal operating current

Question 23

Why are circuit breakers better than fuses?

Answer 23

A circuit breaker can be turned back on, a fuse you have to replace
Circuit breakers turn off faster