electricity

Question 1

what is current

Answer 1

flow of an electrical charge

Question 2

what is the unit of current

Answer 2

ampere A

Question 3

what is potential difference

Answer 3

the driving force that pushes the charge

Question 4

what is resistance

Answer 4

anything that slows the flow of charge down

Question 5

what is the unit of potential difference

Answer 5

volt V

Question 6

what is the unit for resistance

Answer 6

ohm

Question 7

what is the equation of charge flow

Answer 7

charge flow = current * time

Question 8

what is the equation for resistance

Answer 8

PD = current * resistance

Question 9

what graph does a ohmic conductor create and why

Answer 9

current is directly proportional to PD so you get a linear graph

Question 10

what graph does a filament lamp create and why

Answer 10

as current increases the temp of the lamp does so resistance increases

Question 11

what graph does a diode create and why

Answer 11

current only flows in one direction. has high resistance in reverse

Question 12

how does resistance effect an LDR

Answer 12

dependent on light intensity

bright light resistance falls and in dark resistance is highest

Question 13

how does resistance effect a thermistor

Answer 13

dependent on temp

hot resistance falls and when cold resistance increases

Question 14

what is a series circuit

Answer 14

components connected in a line

Question 15

potential difference in a series circuit

Answer 15

is shared

Question 16

current in a series circuit

Answer 16

the same

Question 17

resistance in a series circuit

Answer 17

adds up

Question 18

what is a parallel circuit

Answer 18

components is seperatly connected

Question 19

potential difference in a parallel circuit

Answer 19

the same

Question 20

current in a parallel circuit

Answer 20

shared

Question 21

resistance in a parallel circuit

Answer 21

reduces the total resistance if you add resistor

Question 22

what is AC

Answer 22

current constantly changing direction

Question 23

what is the frequency and PD of AC

Answer 23

50 Hz and 230 V

Question 24

what is the live wire and it’s coulor

Answer 24

provides the AC and is brown

Question 25

what is the neutral wire and it's coulor

Answer 25

completes the current and carries away current and is blue

Question 26

what is the earth wire and it's color

Answer 26

protects the wiring and for safety and is green

Question 27

what are electrical appliances meant to do

Answer 27

transfer energy to components in the circuit when a current flows

Question 28

what is the power of an appliance

Answer 28

energy that is transferred per second

Question 29

equation for energy transferred

Answer 29

power * time

Question 30

what is the power rating

Answer 30

tells you the maximum amount of energy transferred between stores per second

Question 31

what does the power rating tell you

Answer 31

the lower the rating the less electricity it needs and so its cheaper to run an appliance may be more powerful but it can have less efficiency meaning it could transfer the same amount of energy to useful stores

Question 32

what happens when charge goes through a change in PD

Answer 32

energy is transferred

Question 33

equation for energy transferred in terms of charge

Answer 33

charge flow * PD

Question 34

equation for power

Answer 34

PD * current

Question 35

what is the national grid

Answer 35

a giant system of cables and transformers that cover the uk

Question 36

how do power stations meet demand

Answer 36

run below the maximum power out put so there is spare capacity

Question 37

when is demand the most

Answer 37

the morning and night

Question 38

why does the national grid use a high PD

Answer 38

increasing the PD decrease the current which decreases energy lost to the environment

Question 39

why does the national grid use a low current

Answer 39

a high current would use loads of energy as the wires heat up and energy is transferred to the surroundings

Question 40

how do transformers work on the national grid

Answer 40

transformers step up the PD at one end and then bring it down to a safe level

Question 41

how does the earth wire work

Answer 41

wire is connected to case and ground | as the wire is copper there is low resistance allowing the current to follow the path to the ground reducing risk

Question 42

what does a fuse do

Answer 42

melts if the current is too high

Question 43

how does a fuse work

Answer 43

if the case becomes live the large current will flow through the earth wire and melt the fuse

Question 44

how how does static cause sparks

Answer 44

as electrical charge builds up the PD between object and earth increases allowing electrons to jump across to the object or earthed conductor

Question 45

how does static work

Answer 45

insulating materials are rubbed, negatively charged electrons will be scraped off one and dumped on the other

Question 46

what are electric fields

Answer 46

created around any electrically charged object

Question 47

how sparking works

Answer 47

a high PD causes a strong electric field between the charged object and earthed object the field causes electrons in the air to be removed (ionized) when air is inozed it is more conductive so a current flows

Question 48

interaction of charged objects

Answer 48

electric fields of each object interact causing attraction or repulsion as you increase the distance of the objects the strength of the field decrease and the force is smaller