CIE iGCSE Co-Ordinated Science P4.2.5 Electrical energy and electrical power Exam Style Questions Paper 4
Question
12 Electricity can be generated in different types of power stations.
(a) Table 12.1 gives some information about six types of power station.
(i) Use data from Table 12.1 to explain why electricity generation is negatively impacting the environment.
(ii) Nuclear power stations are very expensive to build.
Apart from cost, state one advantage and one disadvantage of generating electricity using wind compared to nuclear.
advantage ……………………………………………………
disadvantage ……………………………………………….
(iii) Use data from Table 12.1 to calculate the mass of natural gas needed to generate the same electrical energy output as 1kg of nuclear fuel.
mass = …………………………………………….. kg
(b) A coal power station generates electricity at a voltage of 25000V.
A transformer is used to step the voltage up to 132000V for transmission.
(i) The step‑up transformer contains 3000 turns on the primary coil.
Calculate the number of turns on the secondary coil.
number of turns = …………………………………………………
(ii) Explain why electricity is transmitted at a voltage of 132000V and not 25000V.
▶️Answer/Explanation
Ans :
12(a)(i) highest percentage of electricity is generated by, coal (and natural gas) / fossil fuels / 61% of production from fossil fuels or
coal and natural gas / 37% of production from coal / 24% of production from natural gas ;
plus
coal / natural gas / fossil fuels, release, carbon dioxide ;
cause climate change / global warming / enhanced greenhouse effect ;
OR
coal / natural gas / fossil fuels, release sulfur dioxide ;
causes acid rain ;
12(a)(ii) (advantage:) no nuclear, waste / accidents / suitable for small scale / no fuel is used / less set up time / AVP ;
(disadvantage:) only works when wind speed is suitable / is less efficient / need lots of turbines (to generate large amounts of electricity) / noise pollution / AVP ;
12(a)(iii) (nuclear output E per kg =) 5.0 × 105 × 0.93 = 4.65 × 105 (MJ) ;
(gas output E per kg =) 45 × 0.49 = 22.05 (MJ) ;
= 4.65 × 105 / 22.05 = 21 000 (kg) ;
12(b)(i) (Ns =) NpxVs / Vp OR 3000 × 132 000 / 25 000 ;
(Ns =) 16 000 ;
12(b)(ii) (increasing the voltage) reduces the current ;
less, energy / power / heat, loss ;