EOUT 2 - electricity & energy

Question 1

2.2 use of insulation

Answer 1

it is in wires & cables
stops a short circuit
no electric shock

Question 2

2.2 use of double insulation

Answer 2

appliances with plastic / wood casing
no chance of a shock - 2 insulators
no need for an earth wire

Question 3

2.2 use of earthing

Answer 3

metal appliances need
- if live wire comes loose
prevents a shock

Question 4

2.2 use of fuses

Answer 4

will blow / melt when too large current flows
breaking circuit
stopping electricity
no electric shock

Question 5

(use of circuit breakers - covered elsewhere)

Answer 5

will trip when too large current
breaks the circuit
can be reset
act quicker than fuses

Question 6

2.3 why a current in a resistor results in the electrical transfer of energy & an increase in temperature & how this can be used

Question 7

2.4 know & use - power current & voltage

Answer 7

power = current x voltage
P = IV

Question 8

2.5 (know &) use - energy transferred current voltage & time

Answer 8

energy transferred = current x voltage x time
E = IVt

Question 9

2.6 know the difference between (mains electricity) alternating current AC and direct current DC

Question 10

2.7 explain why a series or parallel circuit is more appropriate for particular appliances - domestic lighting

Question 11

2.8 understand how the current in a series circuit depends on the voltage & the number & nature of other components

Question 12

2.9 describe how current varies with voltage in wires & how to investigate this

Question 13

2.9 describe how current varies with voltage in resistors & how to investigate this

Question 14

2.9 describe how current varies with voltage in metal filament lamps & how to investigate this

Question 15

2.9 describe how current varies with voltage in diodes & how to investigate this

Question 16

2.10 describe the qualitative effect of changing resistance on the current in a circuit

Question 17

2.11 describe the qualitative variation of resistance of light-dependant resistors with illumination & thermistors with temperature

Question 18

2.12 know that lamps and LEDs can be used to indicate the presence of a current in a circuit

Question 19

2.13 know & use - voltage current resistance

Answer 19

voltage = current x resistance
V = IR

Question 20

2.14 describe current

Answer 20

the rate of flow of charge

Question 21

2.15 recall & rearrange - charge current & time

Answer 21

charge = current x time
Q = It

Question 22

2.16 know that electric current in solid metallic conductors is a flow of

Answer 22

negatively charged electrons

Question 23

2.17 understand why current is conserved at a junction in a circuit

Question 24

2.18 know that voltage across two components connected in parallel is

Answer 24

the same

Question 25

2.19 calculate the currents of two resistive components connected in a series circuit

Question 26

2.19 calculate the voltages of two resistive components connected in a series circuit

Question 27

2.19 calculate the resistances of two resistive components connected in a series circuit

Question 28

2.20 know that voltage is

Answer 28

the energy transferred per unit charge (passed)

Question 29

2.20 know that the volt is

Answer 29

a joule per coulomb

Question 30

2.21 know & use - energy transferred charge & voltage

Answer 30

energy transferred = charge x voltage
E = Q x V

Question 31

4.11 know & use - work done force & distance moved (in the direction of the force)

Answer 31

work done = force x distance moved
W = F x d

Question 32

4.12 know that work done is equal to

Answer 32

energy transferred

Question 33

4.13 know & use - gravitational potential energy mass gravitational field strength & height

Answer 33

gravitational potential energy = mass x gravitational field strength x height
GPE = mgh

Question 34

4.14 know & use - kinetic energy 1/2 mass & speed^2

Answer 34

kinetic energy = 1/2 x mass x speed^2
KE = 1/2 x m x v^2

Question 35

4.15 understand how conservation of energy produces a link between gravitational potential energy, kinetic energy & work

Question 36

4.16 describe power as

Answer 36

the rate of transfer of energy
OR
the rate of doing work

Question 37

4.17 (know &) use - power work done (energy transferred) & time taken

Answer 37

energy transferred = power x time taken