Electricity and Circuits

Question 1

What is current?

Answer 1

The flow of electrical charge

Question 2

What is current measured in?

Answer 2

Ampere (A)

Question 3

What is potential difference measured in?

Answer 3

Volts (V)

Question 4

What is resistance measured in?

Answer 4

Ohms (Ω)

Question 5

What does the total charge through a circuit depend on?

Answer 5

Current and time.

Question 6

What is the equation linking charge and current?

Answer 6

Q=It.

Question 7

Calculate the current if 0.15C of charge flows through in 788 microseconds

Answer 7

190.35533

Question 8

What is potential difference?

Answer 8

The energy transferred per unit charge.

Question 9

What is the equation linking charge and potential difference?

Answer 9

E=QV

Question 10

Calculate the charge if 50J of energy is transferred in an appliance using a 1.5V AA battery.

Answer 10

33.3333333C

Question 11

What is one volt equal to?

Answer 11

1 joule per coulomb.

Question 12

What is the equation linking Resistance and current?

Answer 12

V=IR

Question 13

Calculate the resistance if 40C of charge passes through and produces 880J of energy when 12A pass through.

Answer 13

1.83333333Ω

Question 14

Why does resistance increase with temperature?

Answer 14

Ions vibrate faster when warm so electrons can’t pass through as easily.

Question 15

Should an ammeter be connected in series or parallel?

Answer 15

Series

Question 16

Should a voltmeter be connected in series or parallel?

Answer 16

Parallel

Question 17

What does an ammeter measure?

Answer 17

Current

Question 18

What does a voltmeter measure?

Answer 18

Potential difference.

Question 19

What is LDR short for?

Answer 19

Light dependant resistor

Question 20

Does the resistance of an LDR increase or decrease when light intensity increases?

Answer 20

Decreases.

Question 21

Give 3 uses of LDRs

Answer 21

Automatic night lights, outdoor lighting and burglar detectors.

Question 22

Does the resistance of a thermistor increase or decrease when temperature increases?

Answer 22

Decreases

Question 23

Give 2 uses of thermistors.

Answer 23

Car engine temperature sensors and electronic thermostats.

Question 24

In a parallel circuit, if you add more resistors, will the overall resistance increase or decrease?

Answer 24

Decrease

Question 25

What is the equation linking Energy, time and current?

Answer 25

E=IVt

Question 26

A lamp is connected to the mains for 3 hours and has a current of 6.2A flowing through it. What is the energy transferred in mJ.

Answer 26

15.400800mJ

Question 27

Give one way the heating effect can be useful (not in a circuit designed for heating.)

Answer 27

Fuses

Question 28

What is the equation linking Power and Energy?

Answer 28

P=E/t

Question 29

Calculate the time it would take an 850W microwave to transfer 420kJ of energy.

Answer 29

494.11764705882 s/ 8.23529412mins

Question 30

What is the equation linking power and potential difference?

Answer 30

P=IV

Question 31

What is the equation linking power and resistance?

Answer 31

P=I^2R

Question 32

Calculate the Current flowing through a 700W microwave if the resistance is 7ohms.

Answer 32

10A

Question 33

How many wires are in a typical plug socket?

Answer 33

3

Question 34

What is the frequency and voltage of the mains supply?

Answer 34

50Hz, 230V

Question 35

What colour is the live wire?

Answer 35

brown

Question 36

What colour is the neutral wire?

Answer 36

blue

Question 37

What colour is the earth wire?

Answer 37

green and yellow

Question 38

How does a fuse isolate the circuit if the current gets too high?

Answer 38

It will melt, preventing current from flowing.

Question 39

What are the benefits of using a circuit breaker instead of a fuse?

Answer 39

Turns off quicker than fuses melt, can be reset so it is easier than replacing them.