Circuits

Question 1

what 2 components can be used to provide a potential difference to a circuit

Answer 1

cell and battery

Question 2

what does a voltmeter measure

Answer 2

volts and PD

Question 3

what does an ammeter measure

Answer 3

amps and current

Question 4

what are the 2 types of resistors

Answer 4

fixed and variable

Question 5

what does a filament lamp do

Answer 5

converts electrical energy to light energy

Question 6

what does a motor do

Answer 6

converts electrical energy to kinetic energy

Question 7

what does a diode do

Answer 7

allows current to flow in only one direction

Question 8

what 2 components allow resistance to be changed in relation to the environment

Answer 8

thermistor
LDR

Question 9

what does a thermistor

Answer 9

decreases resistance when temperature increases

Question 10

what does an LDR

Answer 10

decreases resistance when light intensity increases

Question 11

what is an LED

Answer 11

a diode that gives out light when current flows through it

Question 12

what are the 2 types of circuits

Answer 12

series circuits
parallel circuits

Question 13

what is a series circuit

Answer 13

a circuit that contains only one loop

Question 14

what is a parallel circuit

Answer 14

a circuit that contains more than one loop

Question 15

describe the current and PD in a series circuit

Answer 15

• the size of the current is always the same throughout the circuit
• the potential difference is split up between components and will add up to make PD of the whole circuit

Question 16

describe the current and PD in a parallel circuit

Answer 16

the current is split between the different branches and will add up to give the total current
the PD is the same at every point

Question 17

what is an electric current

Answer 17

the flow of electrons

Question 18

what is charge

Answer 18

total current transferred over a certain period of time

Question 19

what is the formula of charge

Answer 19

current * time

Question 20

what is charge measured in

Answer 20

Columbus

Question 21

what is the formula for total energy transferred in a circuit

Answer 21

PD * charge

Question 22

what is ohms law

Answer 22

states that the size of a current flowing through components is directly proportional to the PD

Question 23

what is resistance

Answer 23

a measure of how hard it is for electricity to flow through it

Question 24

what is resistance measure in

Answer 24

Ohms

Question 25

what is the formula for ohms law

Answer 25

PD = resistance * current

Question 26

describe resistance in a series circuit

Answer 26

the resistance will add up to the total resistance of the circuit

Question 27

what is the purpose of an IV graph

Answer 27

shows how the current flowing through a component caries as the potential difference across it varies

Question 28

what does the IV graph of a fixed resistor look like

Answer 28

a straight line

Question 29

what does the IV graph of a filament lamp look like

Answer 29

an S shape

Question 30

why does the shape of a filament lamp look like that

Answer 30

as the potential difference increases, the filament get hotter and the atomic vibrations increase which leads to a greater resistance so the slope of the gradient decreases since the resistance is increasing

Question 31

what does IV graph of a diode look like

Answer 31

the current only flows in one direction. there is a threshold in the forward direction, so the graph is initially flat as there will be a very high resistance in the reverse direction. after that, the resistance does not change.

Question 32

how does the current heating effect work

Answer 32

where there is an electric current flowing energy is dissipated and lost as heat. this is because the elctrons flow through a metal lattice which leads to collisions between the electrons and the metal ions which causes the kinetic energy of electrons to be dissipated as thermal energy

Question 33

what is an advantage of the current heating effect?

Answer 33

some appliances are designed to transfer energy to thermal energy using the current heating effect

Question 34

what are 3 disadvantages of the current heating effect

Answer 34

could lead to appliances catching fire
earthing and circuit breakers need to be placed
energy is wasted

Question 35

what are the 3 equations for power

Answer 35

power = current * PD
power = energy transferred / time
power = current squared * resistance

Question 36

what are the 2 ways a current can flow

Answer 36

AC
DC

Question 37

what is an AC current

Answer 37

a current that alternates. this is where the electrical current changes direction regularly which causes the PD also to be changing

Question 38

what is a DC current

Answer 38

where electrons flow in the same direction

Question 39

what is the voltage and frequency of mains electricity

Answer 39

230V at 50Hz

Question 40

what are the 3 wires in a plug and their colours

Answer 40

earth - yellow and green striped
live - brown
neutral - blue

Question 41

what is the purpose of the earth wire

Answer 41

it is a safety feature. If the live wire comes loose and touches a metal part of the device, it will cause the casing to carry a charge, so anybody who touches it gets electrocuted. however, the heart wire will be connected to the metal casing all allowing the current to flow out through the earth wire

Question 42

what does the live wire do

Answer 42

carries the electrical supply to the appliance

Question 43

what does the neutral wire do

Answer 43

completes the circuit

Question 44

what are 3 safety features of a plug

Answer 44

earthing
fuses circuit breaker

Question 45

what is a fuse

Answer 45

a wire that will melt if too large of a current flows through it and heats it which will break the circuit

Question 46

what is the difference between a fuse and a circuit breaker

Answer 46

circuit breakers can be reused

Question 47

how does a circuit work

Answer 47

will detect when the current is too high and will use magnetic fields to open a switch and break the current