CIE iGCSE Co-Ordinated Science P2.3.1 Conduction Exam Style Questions Paper 3
Question
A room in a house has an electric heater.
(a) Fig. 12.1 shows part of the circuit containing the heater.
Complete the circuit diagram in Fig. 12.1 by adding the correct electrical symbol for a fuse.
(b) When the circuit is switched on, the current in the heater is 3A and the supply voltage is 240V.
(i) Calculate the resistance of the heater.
State the unit of your answer.
resistance = ……………………………….. unit ………..
(ii) The fuse in the circuit needs to be replaced.
Explain why a 5A fuse is used and not a 3A fuse.
(c) Fig. 12.2 shows the heater as part of an underfloor heating system.
(i) When the heater is switched on, thermal energy passes through the solid floor to heat the air in the room.
The temperature of the air in the room increases slowly.
State the method of thermal energy transfer through the solid floor.
(ii) State the method of thermal energy transfer that heats all the air in the room.
(d) Some water spills onto the floor and evaporates.
Describe evaporation in terms of the motion of water molecules.
(e) There are solar cells on the roof of the house.
State one advantage and one disadvantage of generating electricity using solar cells. Do not include the cost.
advantage ………………………………………………………………………
disadvantage ………………………………………………………………….
▶️Answer/Explanation
Ans : 12(a) fuse inserted in gap using the correct symbol ;
12(b)(i) evidence of resistance = voltage / current (in any form) or 240 / 3 ;
= 80 ;
Ω / ohms ;
12(b)(ii) fuse needs to be slightly greater than maximum current (or it would blow in normal use) ;
12(c)(i) conduction ;
12(c)(ii) convection ;
12(d) faster moving / most energetic molecules (leave) ;
(leave) from the surface of the liquid ;
12(e) renewable energy / does not produce CO2 etc ;
need sunlight / only works during the day etc ;