electricity

Question 1

current is

Answer 1

a measure of the flow of elevtrons around the circuit (Amps A)

Question 2

Potential Difference

Answer 2

force driving flow of electrons
- provided by cell/battery
- voltage (V)

Question 3

resistance

Answer 3

Everything that resists or opposes the flow of electrons
- OHMS

Question 4

how does current always flow (in convenction current)

Answer 4

from the positive to the negative

Question 5

what equation connects potential diff, resistance and current

Answer 5

V = IR

Question 6

as long as the resistance stays constant

Answer 6

as the voltage increses the current will increases proportianally

Question 7

if we increases the tempreture

Answer 7

the resistance would also increases temperature

increases, all of the ions in the metal vibrate faster, which makes it harder for electrons to pass along the wire (or in other words, the resistance increases).

Question 8

what does diode do

Answer 8

it only allows the current flow one way in the circuit by making the resistance towatds the opposite direction too high

Question 9

what charge is

Answer 9

a measure of teh total current that flowed within a centain period of time

Question 10

what equation connects charge current and time

Answer 10

Q = I x T

Question 11

what si a fuse

Answer 11

breaks if too much current ges throught it

Question 12

differencce between series and parallel circuit

Answer 12

series circuit only has one loop and all the components are connected toeach other.
On the other hand parallel circuit contains more tahn one loops.

Question 13

potential difeference in a series circuit

Answer 13

is shared across all of the components

Question 14

V total (in series)

Answer 14

V1 + V2 +…. e.g if total V = 12
and componets 1 V = 6 then comp 2 V = 4

Question 15

current is series circuit

Answer 15

same everywhere in the circuit
- ammemter place in series, anywhere
- volmeter connect in parallel to your component

Question 16

current calculation

Answer 16

I = V (total potential diff) / R (total resistance)

Question 17

total resistance in seires curcuit

Answer 17

= sum of individual reisistance of each components

Question 18

how to calc the voltage acroos a single componet

Answer 18

current X resistance across that specific component

Question 19

ohms law

Answer 19

componets with a greater reisistance will always have a higher share of the voltage

Question 20

one rreason parallel is better than series

Answer 20

if one componet in the parallel breaks then the overall circuit still works

Question 21

V total in parallel

Answer 21

V1=V2=V3 …

Question 22

I in parallel

Answer 22

I total = I1 + I2+ I 3….

Question 23

the more componenets we add in parallel =

Answer 23

lower total resistance

Question 24

recall 3 energy formulas

Answer 24

Formula 1:

Energy (E) = Power (P) x Time (t)

Formula 2:

Energy (E) = Voltage (V) x Current (I) x Time (t)

Formula 3:

Energy (E) = Charge (Q) x Voltage (V)

Question 25

recall 2 power formulas

Answer 25

Formula 1: Power (P) = Current (I) x Voltage (V) Formula 2: Power = Current2 x Resistance

Question 26

what is a national grid

Answer 26

giant network of transformers and wires that spreads accross the country to distribute our electricity

Question 27

how do most power sstations works

Answer 27

they create a lot of thermal energy and tehn transfer it into electrical energy

Question 28

when does the electricity demand ususally peaks

Answer 28

in the late afternoon around 6 when evergyone comes back from school and start watching tv cooking etc it is also higher in winter

Question 29

why can we not have a very high current

Answer 29

because very high current generate a lot of heat enegry because of the resistance therefore we lose a lot of energy to the surrounding

Question 30

how does the national grid works

Answer 30

- Electric power is generated at a power station. - Step up transformers increase the voltage and decrease the current. - The electric power is transmitted via the national grid at low current which minimises power loss. - Step down transformers decrease the voltage and increase the current near our homes. - Electric power is wired into our homes at a voltage that is relatively safe to use.

Question 31

descibe in terms of energy how the electricity is produces

Answer 31

Fossil fuel and nuclear power stations work by generating thermal energy. This is used to turn water into steam which can then rise and turn turbines. The kinetic energy of the moving turbines can be converted to electrical energy, which is finally sent out across the national grid.

Question 32

difference between AC and DC

Answer 32

alternating current directing of the current is contantly swaping back and forth, (in uk all main supply is AC) direct current in either - or + charge is always flowing in the same direction

Question 33

what is Hz and V for UK main supplu

Answer 33

50Hz and 230V per second

Question 34

what is oscilloscope

Answer 34

is a device that displays how voltage changes with time

Question 35

direct current is suplied by

Answer 35

cells and batteris

Question 36

what are teh 3 cables in a plug

Answer 36

live, neutral and earth

Question 37

how are plug wires made

Answer 37

they are made up of copper to conduct electricity and are covered in insulating plastic for safety

Question 38

live wire

Answer 38

- brown - provides alternating potential difference - 230V - electricity flows in to the device thought live

Question 39

neutral wire

Answer 39

- completes the circuit by carrying away current - 0v - electricity flows out of the device

Question 40

earth wire

Answer 40

- doesn't carry current -0 V - stop the appliance casing from becoming live - if live wire came loose and touched the casing you can get electric shock - provide an alternative pathway for the current to flow away

Question 41

what are surges and what can cause them

Answer 41

sudden increases in current - when you turn an appliance on or aff - a fault in the circuit or applience

Question 42

What do fuses and circuit breakers do

Answer 42

break the circuit whenever the current gets too high

Question 43

advantage and disadvantages of fuses

Answer 43

adv: - simple and cheap dis: - permanatly broken afetra single surge

Question 44

adv and dis of circuit breakers

Answer 44

adv they cant be permentaly damaged , tehy can eb reset dis more expensive than fuses

Question 45

what is earthing

Answer 45

when an earth wire provides an alternative pathway , any electricity is diverted thought the earth wire

Question 46

what is double insulation

Answer 46

when the entire applience is covered in plastic casing, plastic doesn't conduct electricity so you can;t get an electric shock

Question 47

what is a static electricity

Answer 47

a build up of charge on insulating materials

Question 48

in conductiong materials

Answer 48

the electrons can flow back so no charge is ever buil up

Question 49

in insulating material

Answer 49

electrons can' t flow back so the tranfer caused by the friction cause positive static charge on th ematerial that has lost the electrons and negative on teh one that gained

Question 50

what happens if an object just keeps gaining the electrons

Answer 50

the size of the zharge will increase therefore the potential difference woudl develove between the charged material and the any earthed object. If the PD high enogh then the elctrons can jump thought the gap which causes the spark.

Question 51

what direction do the elctric field arrows always go in

Answer 51

from positive to negative

Question 52

relashionship betweenn the distance and the strenght of the lectric field

Answer 52

the field is strongest close to the particle and it egts weaker the further away you get

Question 53

nothing

Answer 53

you are the best