1.
(a)
A = battery (of cells)/cells/cell
B = thermistor/temperature dependent resistor
C = transistor
D = LED/light emitting diode
E, F, G = resistors
each for 1 mark
5
(b)
ideas that
(resistance) falls
from 3000
to 200
units – ohms/ – referred to at least once
each for 1 mark
4
(credit quickly at first then more slowly with 2 marks)
(max 4 for part (b))
(c)
any figure in the range 22 – 26 (inclusive)
gains 1 mark
2
but
24
gains 2 marks
[11]
2.
(a)
current rises/starts lower/starts from zero
for 1 mark
3
ideas that: *
smaller/only 0.45 (A) change in current
quicker/only 2 (ms) for current to settle
slightly lower/0.45 (A) final current
maximum only 0.45 (A) rather than 1.5 (A)
(*must compare e.g. “only...” or state figure from first graph)
any 2 for 1 further mark each
(b)
resistance of filament rises as temperature rises/higher at operating temperature
resistance of X falls as temperature rises/low(er) at operating temperature
total resistance stays roughly the same as temperature rises
so current stays roughly the same as temperature rises
(must be related to previous point)
4
resistance of X falls faster at first than resistance of filament rises
so current rises (must be related to previous point)
operating resistance slightly increased
so operating current slightly reduced
(must be related to previous point)
resistance of X high at start
so current zero/low
each gains 1 mark
(must be related to previous point)
(to a maximum of 4)
[7]
watford grammar school for boys
1
3.
(a)
idea that
4
it/current increases (with voltage)
gains 1 mark
but
current increases steadily (with voltage)
(allow in proportion)
gains 2 marks
no current at first
gains 1 mark
but
no current until voltage is more than 0.3 (volts)
gains 2 marks
(b)
(i)
reverse component X/power supply/change battery round
for 1 mark
(ii)
idea that
X doesn’t conduct in opposite/let current through/no current
(in opposite direction)
(credit X is a diode)
for 1 mark
2
[6]
4.
(a)
ideas that
5
current increases with voltage
gains 1 mark
but
current increases steadily with voltage
gains 2 marks
(allow in proportion)
no current at first
gains 1 mark
but
no current until voltage is more than 0.3 (volts)
gains 2 marks
no current whatever the voltage is X/diode/power supply reversed
for 1 mark
watford grammar school for boys
2
(b)
sine-wave current for only half of each cycle
gains 1 mark
2
but
s-w current for less than each half cycle
gains 2 marks
[“Loops” must be narrower L  R than in top diagram and with wider spaces between]
[7]
5.
(i)
(ii)
either
210 C
3
or
1260 (joules of energy transferred)
unit not required
1
210
1
coulomb(s) C
allow J/V
1
either
0.7 A
3
or
charge = current × time
or 210* = current × 300
(1)
or Q = It
or* same as candidate’s answer to
part (a)(I) provided correct unit given in part (a)(i)
or* as follows from above
current = 0.7*
amp(s) or A
(1)
(1)
[6]
6.
(a)
series circuit
1
all four components must be included
if a battery included the neatness mark may still be awarded
(b)
circuit fully functional or properly
connected
this is the neatness mark
do not credit a parallel circuit with one switch controlling both
components
1
case or outer parts are made of plastic
or insulator or non-metallic
1
there is no electrical pathway between
inner and outer insulation
accept no connection between inner and outer part
do not credit two layers of insulation
1
watford grammar school for boys
3
(c)
(i)
(ii)
[A]
power = voltage × current
accept P = V I or
W=VxA
or any transformation
1
[B]
1600 ÷ 230 =current
1
6.96 or 7
accept with no working for two marks
accept 6.95
in [A] award a mark for a triangle if calculation correctly
performed
1
[A]
voltage = current × resistance
accept V = I R or any
transformation
1
[B]
230 ÷ 7 = overall R = 33
accept 230 ÷ 6.96 = overall R = 33
1
resistance of motor = 33 – 20 = 13
accept with no working for two marks
do not credit negative answer
accept consequential errors from c(i)
in [A] award a mark for a triangle if calculation correctly
performed
1
[10]
7.
(a)
wire gets hot
1
and gives out light or glows
1
(b)
to get the maximum electricity or
power to the filament or to not waste energy
credit not to get hot or not to melt credit so that current can flow
easier
1
(c)
any two from
2
insulator
transparent
strong
[5]
8.
(a)
Formula mark
P=V×I
accept P = VI or W = V 5 A or
any transformation
1
Substitution mark
I = 900 ÷ 230
1
Calculation mark
3.9
accept 3.9 or 3.91 or 4 for
three marks with no working
1
watford grammar school for boys
4
(b)
900 + 1300 = 2200
÷ 230 = 9.6
accept 9.57 to 9.6 or 10 for both marks
with no working
1
(c)
1.2 + 0.45 = 1.65
1
× 0.5 = 0.825
accept 0.8 or 0.83 for both marks
with no working
1
any one from
1
(d)
use less energy (to cook something)
accept fewer energy losses or
use less electricity
cook faster
do not credit a cost argument
about buying two different ovens
[8]
9.
(a)
(b)
(i)
EITHER
30000 (2) joules/J (1)
or 30 kilojoules/kj
3
OR
power × time = energy
1
time = 120 (seconds)
1
(ii)
vibration (of the food processor /
some part of the food processor / the food)
1
(i)
step-up
1
transformer
1
any two from
2
(ii)
the current is low(er)
(so) power / energy / heat losses are less
(so) it is cheaper
(iii)
any two from
2
difficult to insulate
do not credit danger to health due to
electromagnetic field(s); the danger is
unproven and if it exists would not be
reduced by using low voltages
and high currents
watford grammar school for boys
5
need to be carried on (high) pylons
(or) (underground) along well
insulated buried cables
danger of lethal electric shock
accept danger of electrocution
do not credit just danger of electric shock
possible discharge to earth
transformers needed which adds to cost
note reference to resistance is incorrect
[10]
10.
(a)
any two from
2
(risk of) cutting (through the) cable
accept cutting the wire
grass may be wet
or it may rain
wires may be loose (because cable
experiences a lot of movement)
accept cable may be loose
(risk of) touching exposed part(s)
(b)
some current will go through (the rest of)
the lawnmower / the user / to earth
do not credit any reference to the
electromagnet
(c)
(i)
charge = current × time
or any transposed version
accept Q = I × t
or any transposed version
accept C = A × s
or coulombs = amperes × seconds
or any transposed version
or
or
Q
I
t
1
1
Q
t I
but only if subsequently used correctly
watford grammar school for boys
6
(ii)
EITHER
1200 microcoulombs / C
or 1.2 millicoulombs / mC
or 0.0012 coulombs /C
3
OR
correct arithmetic
either
converting milliamps to amps
and milliseconds to seconds
or correct multiplication
1
unit given as coulombs /C
or millicoulombs / mC
or microcoulombs / C
example :
charge = 30 × 40 = 1200 millicoulombs
should be credited with 2 marks
[7]
11.
(a)
(b)
(i)
variable resistor
accept rheostat
1
(ii)
potential difference =
current × resistance
accept V = IR or any correct combinations
1
(i)
as the potential difference increases, the current increases
accept it increases
1
at low values of the potential
difference the current is (directly) proportional
accept at low values of the potential difference (the filament)
obeys Ohm’s law
1
or
at higher values of potential difference
the current is not (directly) proportional
or
accept at higher values of the potential difference (the filament)
does not obey Ohm’s law
accept it increases but not proportionally for 2 marks
the resistance (of the filament) increases
1
the temperature (of the filament) increases
1
[6]
12.
(a)
A - fuse
B - (cable) grip
for 1 mark each
2
(b)
X - brown/red
Y - green + yellow/green
Z - blue/black
for 1 mark each
3
watford grammar school for boys
7
(c)
any plastic/rubber
for 1 mark
1
(d)
(i)
1
earth
for 1 mark
(ii)
(e)
metal appliance needs earthing/safety qualified
for 1 mark
cut less insulation on earth;
neutral wire needs connecting;
fit fuse properly;
cable grip needs to be an outer cable
or allow identifying faults
for 1 mark each
1
4
[12]
13.
level drops as petrol used;
causes circuit resistance to increase;
causes current to decrease
for 1 mark each
or
if change not specified;
(one correct and two vague statements gains 2 marks,
three vague statements gains 1 mark)
e.g. level changes;
)
so resistance changes; ) = 1 mark
so current changes
)
[3]
14.
(a)
Current = 0.4A (1)
R = V/I or 240/0.4 (1)
R = 600 ohm (1)
3
(b)
Doubles
2
gets 2 marks
OR gets bigger
gets 1 mark
(c)
P = V.I or 240 × 0.4
P = 96W
for 1 mark each
2
(d)
1 = 0.2A
P = 48W
2
for 1 mark each
BUT may get equation mark here if not in (c)
watford grammar school for boys
8
(e)
P = V.I.t (1)
P = 240x0.2 × 6 × 3600
OR P = 48 × 6 × 3600
gets 1 mark
3
P = 1036800 W
gets 1 mark
[12]
15.
(a)
becomes (electrically) charged
or description of electron movement
for 1 mark
1
(b)
comb attracts paper
for 1 mark
1
(c)
charge/electricity gone
to Earth/body
for 1 mark each
2
[4]
16.
(a)
to switch on/off
independently OWTTE
for 1 mark each
2
(b)
9
1
for 1 mark
(c)
B and E
1
for 1 mark
(d)
1
Two/least number of LED used
for 1 mark each
2
[6]
17.
(a)
(b)
(c)
(i)
Ends have charge
Which is opposite on each rod
2
(ii)
Attracts
1
(i)
Repulsion
1
(ii)
Ends have same charge
1
Electrons move between cloth and rod
Where gather is negative
Where move from is positive
3
[8]
18.
(a)
(i)
S3
1
for 1 mark
(ii)
S1, S2 and S3
for 1 mark
watford grammar school for boys
1
9
(b)
(c)
(i)
increases/current passes through heaters/
current unaffected in fan
for 1 mark
1
(ii)
(fan) blows/air moving
prevents dryer overheating
for 1 mark each
2
(i)
brown
blue
2
any order
for 1 mark each
(d)
(ii)
earth/green and yellow
for 1 mark
1
(iii)
(case is) plastic
plastic does not conduct (electricity)
for 1 mark each
2
(i)
1300/power
for 1 mark
1
(ii)
time/units of time
for 1 mark
1
[12]
19.
(a)
(i)
13A
1
for 1 mark
(b)
(ii)
fuse heated
melts owtte / blows / burns out Not explodes / burns
circuit breaks
any 2 for 1 mark each
2
(i)
2750 × 6 or 2.75 × 6
gains 1 mark
2
but
16.5
gains 2 marks
(ii)
2750 × 6 × 7 or 2.75 × 6 ×7 or (b)(i) × 7 or kW h × cost / kW h
gains 1 mark
2
but
115p or 116p or 115.5p or £1.16 or £1.15
gains 2 marks
[7]
20.
(a)
earth
yellow and green
accept green and yellow
live
brown1
neutral
blue
watford grammar school for boys
1
1
10
(b)
(c)
(i)
path shows electricity flowing from
washing machine through to
the person (and on to earth)
ignore direction of arrows
1
(ii)
electricity flows through earth wire
(to earth) or goes to ground
not escaping electricity
not fuse wire blowing
1
not through the person or miss the
person or not electrocuting
not electric shock
1
hairdrier
1
hairdrier needed for second mark except allow double insulated
if iron or fridge but not plastic case
double insulated or plastic case
accept ‘It’s made of plastic’
accept ‘it does not conduct’
1
[8]
21.
(a)
(i)
(ii)
(b)
similar charges repel
read both (a)(i) and (ii) together and credit correct points
anywhere in (i) and (ii) (provided not negated by wrong
answers)
1
droplets evenly spaced or
droplets do not join
i.e. 4 points:
 like charges repel
 unlike charges attract
paint droplets spreading
 paint sticking to car
1
opposite charges attract
1
paint sticks to car body or
paint attracted to car body (if not
given in (i) can be credited in (ii) or
paint reaches hidden parts of car body
1
during flight friction or
movement between air and aircraft
alternative scheme for first two marks : –
friction between fuel and pipe -first mark
static/charge (on pipe) - second mark
1
causes addition or removal of charge
from aircraft
accept aircraft becomes charged
1
watford grammar school for boys
11
wire connects aircraft to earth
accept wire earths the aircraft or statement about discharging
plane
1
reduces risk of spark or ignition of
petrol (vapour) or explosion or fire
do not accept answer about man getting a shock
1
[8]
22.
(a)
(b)
horse completes circuit between wire and earth or horse earths the wire
1
charge or electrons or current or electricity flows through the horse
1
two from:
2

RCB breaks circuit when it detects a difference between
currents in live and neutral wires

fuse breaks circuit only when fuse rating exceeded or when it melts

RCB is resettable
(ii)
500 (ms)
leakage current = 0.02A 1 mark only
2
[6]
23.
(a)
C
1
award mark if A and B identified as not filament lamp
(b)
resistance increases
negated by wrong statement e.g. current goes down
1
as the lamp gets hot
accept as current (through lamp) or voltage (across lamp)
increases
do not accept non-ohmic reason independent of choice of
component
1
ammeter wire and battery only in
series
non standard symbols acceptable if correctly identified
(labelled) for ammeter, voltmeter and battery
1
voltmeter only in parallel with wire or
battery
all in series or ammeter in parallel neither of these two marks
awarded
1
all symbols correct
ignore lines drawn through centres of symbols
(c)
(i)
voltage = current × resistance
accept V = I × R
accept volts = amps × ohms
do not accept V = C × R
accept
watford grammar school for boys
1
V
I R
12
if subsequent method correct
(ii)
30
2
accept correct substitution for 1 mark (9/0.3)
ohms
(iii)
1
accept correct symbol 
goes up
must be a comparison
accept calculation if answer is larger than c (ii)
1
[11]
24.
(a)
(i)
7
1
(ii)
(electrical) power = voltage x current
accept P = V × I (correct standard symbol)
accept watts = volts x amps
accept a correct rearrangement
1
P
accept
V
I
if subsequent use of
(iii)
is correct
1610
or
their (a)(i) × 230
1.61 kW = 2 marks
do not accept 7 × 240
1
watts
1
accept watt
accept W
accept .J/s
(iv)
melts
1
accept burns out
accept blows
accept breaks
do not accept stops working
do not accept burns
(b)
(i)
current greater than 13(A)
or
current exceeds fuse rating
or
current 15(A)
do not accept too much current
unless qualified
1
if live wire touches case
accept if case becomes live
accept metal for case
1
watford grammar school for boys
13
(ii)
current flows to earth or ground
or
fuse melts
or
stops iron becoming live
accept electricity flows to earth
do not accept - you will get a shock
accept with no earth (wire) you would or could get a shock for
1mark
1
(outer) case is made of insulator
accept outside is plastic
accept outside is not made of metal or conductor
1
cable is (also) insulated
accept wires for cable
do not accept it has two layers of insulation without explanation
do not credit answers in terms of heat
[10]
25.
(a)
(i)
force = mass  acceleration
accept F = m  a
accept upper or lower case letters
accept equation using correct units
accept
1
F
m a
if subsequent method correct
(ii)
0.007
2
allow 1 mark for correct transformation or substitution
(b)
(i)
charge = current  time
allow Q = I  t
accept upper or lower case letters
accept equation in correct units
do not accept a mix of quantity unit and symbol
accept
1
Q
I
t
if subsequent method correct
do not accept C for current
(ii)
0.0008
1
[5]
watford grammar school for boys
14
26.
(a)
(i)
potential difference = current
× resistance
accept voltage or pd for potential difference
accept V = I × R
accept correct transformation
do not accept V = C × R
do not accept V = A × R
1
V
accept
I
R
provided
subsequent use of  correct
do not accept an equation expressed in units
(ii)
46
3
credit correct transformation for 1 mark
allow 1 mark for use of 11.5 V or
division of final resistance by 20
a final answer of 920 gains 2 marks only
(iii)
(b)
ohm(s)
accept symbol 
do not accept  s
unit / symbol mark can be awarded in (iii) provided unit /
symbol is omitted in (ii)
1
920 (ohms) or their (a)(ii) × 20
1
as temperature increases, resistance increases
accept hotter for temperature increase
do not accept a reference to resistance only i.e. it / resistance
goes up
1
[7]
27.
(a)
B E A D
3
allow 1 mark for each letter in the correct place, to a maximum
of 3 marks
(b)
(a spark) may cause the (petrol vapour) to explode / ignite
accept petrol for (petrol vapour)
accept catch fire for explode
1
connect tanker to earth with a (conducting) wire / chain or earth the tanker
accept ground for earth
1
watford grammar school for boys
15
(c)
Quality of written communication
for a logical sequence
1
any two from:
2
 when current greater than fuse rating / value
accept when current too great for appliance
do not accept ‘if there is too much current’
do not accept voltage or electricity
 fuse (becomes hot and) melts / burns out
accept fuse blows / breaks
 circuit is broken
accept circuit switched off
this cannot score credit on its own
[8]
28.
(a)
loses negative charge / electrons
do not accept positive charge transfers to the comb
do not accept friction
1
(b)
A
attract
1
B
repel
1
C
attract
1
(c)
FADE
3
allow 2 marks for 2 letters in the
correct place
allow 1 mark for 1 letter in the
correct place
[7]
29.
(a)
electrons / negative charges are repelled
do not accept converse
implied movement of ‘positive charges’ negates the mark
1
(b)
(i)
1
energy (transferred) = potential
difference  charge
accept pd or voltage for potential difference
accept E = V  Q
accept W = V  Q
accept
E
V
Q
provided subsequent method correct
21 600 000 000 or 2.16  1010
accept 21 600 000 kilojoules for both marks
allow 1 mark for an answer of
21 600 000 joules
copper is a good (electrical)
(ii)
(c)
watford grammar school for boys
2
1
16
conductor or copper has a low
resistance
accept allows electrons / electricity to flow easily
ignore heat
provides path for electrons /
electricity / lightning to earth /
ground / metal plate
do not accept in terms of heat / energy
do not accept attracts lightning unless explained
1
[6]
30.
(a)
(b)
(i)
droplets will repel (each other)
giving an even spray / layer of paint
1
1
(ii)
attracts (all) the paint droplets
paint covers entire frame / little paint wasted
accept paint front and back at same time
accept spreads to hard to reach places
1
1
any (electrostatic) charge
1
will flow to earth (through the floor)
1
reducing the risk of a spark
allow reducing the risk of an electric shock
1
[7]
31.
the live wire to touch the metal case
1
a large current is drawn from the live which flows through earth wire / to earth
accept if there were no earth and
someone touched the appliance
current would flow through them to
earth
1
the current melts the fuse, switching off the appliance
an answer given in terms of there
being no earth gains a maximum of 2 marks
1
[3]
watford grammar school for boys
17