Revision Sheet 1 Applying your knowledge Electricity.
1 Assess the impact of shutting down all coal power stations in NSW
The shutting down of all coal power stations is probably essential for the sake
of the planet to prevent global warming but it would have serious economic
and therefore social consequences for the people of NSW.
Positive
Much Less CO2 will enter the atmosphere.
Reducing global warming.
People will probably become more energy
efficient as alternative sources of
electricity are so expensive.
The use of solar and wnd power will
probably be useful.
Scientific development of alternative
energy sources will be hugely important
and will receive massive boost of funds
from govt. Leading to scientific discovery
Negative
Social stress will occur as families cannot
pay their electricity bills as coal is by far
the cheapest way for us to make
electricity
Many elderly people may end up in cold
homes.
Nuclear power will be put into service and
this creates a huge disposal problem for
the radioisotopes produced.
Nuclear power could lead to mining in
Aboriginal sacred land.
It will also lead to innovation in house
design.
School fees would increase and many
schools would lose customers.
People will probably get outside more as
running household appliances will be so
expensive
Food prices would rise for shops and
farmers to cover the cost of electricity.
People could go back to wood fires
creating smog in Sydney.
2 (a) the charge will be shared ie 4x10-5C per ball.
(b)
3 This is an inverse square force so the force will reduce to 1/16th F.
(b) Neither they are the same (Newton’s third law)
4 V=W/q=600/1.5=400V
5
(a) the ball is suspended and so the force of gravity (mg) must equal the force
due to the electricity (Eq) As long as we know the size of mg we know the size
of Eq
F=mg =10-4x 9.8=9.8x10-4
(b)
F=Eq=
9.8x10-4=Ex10-6
E=980 NC-1
(c) In this situation we would double the field. This would make the electric
force stronger than the gravity force. The gravity force was 9.8x10-4 down.
The Electric force in the opposite direction of 19.6x10-4 Adding these two
forces as vectors gives 9.8x10-4 up. Now use F=ma. 9.8x10-4 up=10-4xa
and hey presto it will accerate up at 9.8m/s/s
6
They are oppositely charged. P is positive Q is negative AND Q has a greater
Magnitude of charge.
7 D
8 C
9 (a) V=IR so I=V/R so I=240/60= 4 Amps.
(b) P=VI so P=240x 4=960W
(c) (You don’t have to know this..but you may be clever enough to work it out.)
The answer is 43.75s
10 This circuit is weirdly drawn The top and bottom resistors are in parallel
but not the middle one. Total resistance for this circuit is
2+(1/2+1/2)-1=3Ω
V=IR So 6=IX3 So I=2Amps.
11 (a) The resistance is 48Ω
(b) RT=(1/4+1/48)-1 = 3.69Ω
12 A2=0.6A
A3= 0.3A
13 R=1+(1/4+1/4)-1+1=4Ω
14
15 When the switch is open the circuit is effectively a 1Ω and a 2Ω in series.
so total resistance is 3Ω A current of 1A suggest the voltage of the batter is
3V. So when you close the switch the total resistance changes but the battery
voltage stays the same. V=IR 3=I x [1+(1/2+1/2)-1] therefore I=1.5Amp.
16 R=[1/50 + 1/100]-1 =33.3Ω
(b) 25V
(c) V=IR 25=Ix50 I=0.5Amps
17
6V
?A
?
?V
?
?V
(b) Yes the total on the voltmeters =3V.this is the sum of the two 1.5 V
batteries in series…(You don’t need to know the last bit.)
(c) V=IR 2=20xR so R=0.1Ω very approx as the meters are hard to read!!
(d) P=VI = 0.8 x 20=16 Watts.
18 a