Final Test: Edexcel Generating Electricity and Energy P1.5 P1.6 (15 Marks)

SOLUTIONS

Final test: Edexcel Generating Electricity and Energy P1.5 P1.6 (15 marks)

a. A power station generates electricity at a rate of 30MW. How many Joules of energy does it produce in

1 second? (circle the correct answer)

a.A. 3 000J

a.B. 300kJ

a.C. 30 000 000J

a.D. 300MJ

(1 mark)

b. A transformer has a primary voltage of 400V and 100 primary windings. If the secondary turns are 25, what will be the output voltage? (tick the correct box)

Vp = Np

Vs Ns

100V 40V

16V 1600V

(1 mark)

2. The diagram shows the main stages in producing and transmitting electricity. Label the parts numbered 1 to 4.

www.pixl.org.uk The PiXL Club Ltd, Company number 07321607 http://www.bbc.co.uk/schools/gcsebitesize/science/images/20_the_national_grid.gif

1 Boiler/steam generator 2 Turbine

3 Generator 4 Transformer

(4 marks)

3. An electric light bulb transfers 500J of electricity into 70J of useful light with the remaining 430J energy being lost as heat. Calculate the efficiency of the light bulb.

Efficiency = energy usefully transferred X 100 = __ 70 X 100__ = 14

total energy supplied 500

Efficiency of the bulb = 14%

(3 marks)

4. QWC Describe the advantages and disadvantages of replacing a coal fired power station with a nuclear power station.

QWC Suggested marking guidance (Total 6 marks) Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response. Teachers should and apply a ‘best-fit’ approach to the marking. 0 marks Level 1 (1-2 marks) Level 2 (3-4 marks) Level 3 (5-6 marks) No relevant Attempt at a description 1-2 Brief description 3-4 marking points. Clear description almost all marking content. marking points. There is reasonable accuracy in points. The spelling, punctuation and spelling, punctuation and grammar, The answer shows almost faultless grammar are very weak. although there may still be some spelling, punctuation and grammar. errors

 Coal fired power station produces a lot of greenhouse gases  Much more coal required than nuclear fuel  Coal has a slower start-up time

 Nuclear fuel can be very dangerous (radioactive)  Decommissioning of nuclear power station is expensive  Terrorist threat to nuclear power stations  Coal is expensive to mine and transport

(6 marks)