CIE iGCSE Co-Ordinated Science P4.2.5 Electrical energy and electrical power Exam Style Questions Paper 2
Question
A heating element in an electric kettle has a resistance of 24 Ω.
When the kettle is connected to a 240V supply, it takes 2.5 minutes to boil some water.
How much energy is used to boil the water?
(A) 16 J
(B) 960 J
(C) 6000 J
(D) 360 000J
▶️Answer/Explanation
Ans: D
Question
An electric motor is connected to a power supply by insulated wires. The circuit is protected by a fuse, but the wires become hot.
Which change prevents the wires from becoming so hot?
(A) Connect a second identical fuse in the circuit.
(B) Use a fuse with a higher current rating.
(C) Use thicker connecting wires.
(D) Use thicker insulation on the connecting wires.
▶️Answer/Explanation
Ans : C
Question
Electrical energy from a power station is transmitted over a large distance. A 100% efficient
transformer is used near to the power station. This transformer reduces the energy that is wasted thermally in the transmission cables.
How does the transformer reduce the energy that is wasted?
(A) It decreases the power transmitted so the current and the voltage are both larger.
(B) It decreases the power transmitted so the current and the voltage are both smaller.
(C) It increases the current so the voltage is smaller.
(D) It increases the voltage so the current is smaller.
▶️Answer/Explanation
Ans: D
Question
A kettle is connected to a 230V mains supply. The current in the kettle is 10A.
How much energy is transferred in 3.0 minutes?
(A) 12.8 J (B) 767 J (C) 6900 J (D) 414 000J
▶️Answer/Explanation
Ans: D