electricity

Question 1

What is current?

Answer 1

the rate of flow of charge

Question 2

What are electrons?

Answer 2

negatively charged particles

Question 3

Where can a current flow?

Answer 3

through a component if there is a voltage across that component

Question 4

What is the unit for current?

Answer 4

ampere (amp) A

Question 5

What does the voltage do?

Answer 5

what drives the electrical current through the circuit = electrical pressure

• also called potential difference

Question 6

What is the unit for voltage?

Answer 6

volt, V

Question 7

What is resistance?

Answer 7

anything in the circuit which slows the flow down

Question 8

What causes a higher overall resistance?

Answer 8

if you add more components or the circuit

Question 9

What is the unit for resistance?

Answer 9

ohm, Ω

Question 10

What does the ammeter measure?

Answer 10

current in amps

Question 11

Describe the relationship between voltage and flow

Answer 11

if you increase the voltage, then more current will flow

Question 12

Describe the relationship between voltage and resistance

Answer 12

if you increase the resistance, then less current will flow

Question 13

Where should the ammeter be placed?

Answer 13

series

Question 14

What does the voltmeter measure?

Answer 14

voltage in volts

Question 15

Where should the voltmeter be placed?

Answer 15

parallel

Question 16

What are the UK mains electricity supply?

Answer 16

230 volts

Question 17

What is an a.c. supply?

Answer 17

alternating current, the current is constantly changing direction

Question 18

What do cells and batteries supply?

Answer 18

direct current

Question 18

What does direct current mean?

Answer 18

current keeps flowing in the same direction

Question 19

LED - what is it

Answer 19

light emitting diode - emit light when a current flows through them in a forward direction

used for numbers on digital clocks and in traffic lights

they don’t have a filament which can burn out

Question 20

LEDs definition

Answer 20

Light-Emitting Diodes

Question 21

What do LEDs do?

Answer 21

emit light when a current flows through them in the forward direction

Question 22

What do LEDs indicate?

Answer 22

the presence of current in a circuit

Question 22

What are LEDs used for? (examples)

Answer 22

numbers on digital clocks, traffic lights and remote controls

Question 23

What are LEDs often used for?

Answer 23

used in appliances to show that they are switched on

Question 23

LDR definition

Answer 23

Light dependent resistor

Question 24

How do LDRs react when in different lighting? (2)

Answer 24

• in bright light = resistance falls
• dark light = resistance is the highest

Question 25

What do LDRs do?

Answer 25

a special type of resistor that changes its resistance depending on how much light falls on it

Question 26

What are LDRs used for? (examples)

Answer 26

electronic circuits –> burglar detectors

Question 27

What is a thermistor and what is it used for?

Answer 27

a temperature dependent resistor and used as a temperature detectors

Question 28

thermistor in hot

Answer 28

resistance drops

Question 29

thermistor in cold

Answer 29

resistance goes up

Question 30

What are thermistors used for? (examples)

Answer 30

car engine temperature sensors, thermostats, fire alarms