CIE iGCSE Co-Ordinated Science P1.6.3 Energy resources Exam Style Questions Paper 3
Question
A Coal burns to produce thermal energy.
B A turbine drives a generator.
C Steam is produced.
D Steam turns a turbine.
E Thermal energy boils water.
Use two lamps in each circuit.
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic P1.6.3 — Energy resources (Part (a))
• Topic P1.6.3 — Energy resources / efficiency (Part (b), (c))
• Topic P4.3.2 — Series and parallel circuits (Part (d))
▶️ Answer/Explanation
(a) coal → non-renewable AND polluting; geothermal → renewable AND non-polluting
Coal is a fossil fuel that cannot be replaced once used up, and burning it releases pollutants.
Geothermal energy comes from the Earth’s heat, which is naturally replenished and produces no pollution.
(b)(i) A → E → C → D → B → electricity is generated
Coal burns (A), releasing thermal energy that boils water (E), producing steam (C).
The steam turns a turbine (D), which drives a generator (B) to produce electricity.
(b)(ii) 100 °C
Water boils at 100 °C at standard atmospheric pressure.
(c)(i) The percentages add up to 100%
Since \( 25 + 15 + 60 = 100 \), all the input energy is accounted for in the listed outputs, showing none is lost overall.
(c)(ii) Most of the energy output is wasted as thermal energy, with only 25% converted into useful electrical energy
A power station is inefficient because the majority (75%) of energy ends up as unwanted heat rather than being converted into useful electrical output.
(d)(i) Parallel circuit: two lamps each on separate branches across the battery; Series circuit: two lamps in a single loop one after another
In a parallel circuit, each lamp is on its own branch, connected independently across the supply.
In a series circuit, both lamps share the same single current path, one after the other.
(d)(ii) Each lamp can be switched on/off independently, or if one lamp fails the others continue to work, or each lamp gets the full mains voltage
In a parallel circuit, the failure of one lamp does not break the circuit for the others, and each lamp receives the same full voltage as the supply.
Question
Topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic P4.3.1 — Circuit diagrams and circuit components
• Topic P1.6.3 — Energy resources
• Topic P4.2.4 — Resistance
• Topic P4.2.5 — Electrical energy and electrical power
• Topic P2.2.2 — Melting, boiling and evaporation
▶️ Answer/Explanation
(a) Motor: circle with ‘M’ inside. Variable resistor: rectangle (or zigzag) with a diagonal arrow across it.
The motor symbol indicates conversion of electrical energy to kinetic energy.
The arrow on the variable resistor symbol shows that its resistance can be adjusted, making it useful for controlling current in circuits such as dimmer switches or volume controls.
(b) Advantage: renewable / produces no greenhouse gases. Disadvantage: does not work at night / only works in sufficient sunlight.
Solar cells convert light energy directly into electricity with no fuel costs and zero emissions during operation.
However, their output depends entirely on sunlight availability, making them unreliable without battery storage, and initial installation costs can be high.
(c)(i) Current in the washing machine:
\(I = \dfrac{P}{V} = \dfrac{2500}{230} \approx \textbf{11\,A}\)
Using \(P = IV\) and rearranging for current, dividing the power (2500 W) by the supply voltage (230 V) gives approximately 10.87 A, which rounds to 11 A to 2 significant figures.
(c)(ii) Resistance of the heating element:
\(R = \dfrac{V}{I} = \dfrac{230}{3.0} \approx 77\,\Omega\)
Applying Ohm’s law \(V = IR\) and rearranging gives resistance as voltage divided by current.
The high resistance of the element is what causes electrical energy to be converted efficiently into heat.
(c)(iii) The most energetic particles near the liquid surface have enough kinetic energy to overcome intermolecular attractions and escape into the gas phase.
Because it is the fastest-moving particles that escape, the average kinetic energy of the remaining liquid falls, causing the liquid to cool.
Evaporation can occur at any temperature, unlike boiling which requires the entire liquid to reach a fixed boiling point.