P6 Science Prelims (MGS/2023/Booklet B/Q37): Systems: Electricity
5 mark question
Science | P6, Prelims (MGS/2023/Booklet B/ Q37) | Electricity
Try this common question on electrical circuits and test if you can tell the difference between Parallel and Series circuits. This walkthrough helps solidify your understanding and apply your concepts to solve an actual Prelim Science question.
The Question (5 marks)
Anna wanted to install a ceiling fan with a light in her living room.
The fan comes with two switches, S1 and S2, that allow her to turn the fan on with or without light as described in the table below. Each switched can be turned on to position A or B in the circuit.
(a) The diagram shows part of the circuit. Complete the circuit so that it will work as described. [2]
Let’s answer the question!
(a) Explanation: From the chart (1st row), we note that when both Switches are turned on to A, both the fan and light are turned on. Therefore, we must draw a circuit that connects both the fan and the light bulb when the switch is connected to A. Don’t forget to add the battery!
Next, we go to the other case where we see a “Yes”, and that is in line 4, where both switches at B will allow ONLY the fan to be switched on (not the light). This is important and from this, we can solve the problem by simply adding on a complete circuit for the fan that connects to the B switches.
And that’s it! you’ve sold this question. Congratulations!
(b) Anna set up another two electrical circuits, Y and Z with different bulb arrangements. She added a bulb to each circuit and recorded the brightness of the bulbs in a graph as shown below.
(i) Based on the above information, state the arrangement of bulbs for each circuit. [1]
Circuit Y:
Circuit Z:
(ii) Besides changing the number and arrangement of bulbs, suggest what Anna can do to increase the brightness of bulbs in circuit Z. Explain your answer. [2]
Let’s answer the question!
b (i) Explanation: We are comparing how the bulb brightness changes as the number of bulbs increases. In circuit Y, the brightness remained constant. In Circuit Z, the brightness decreased. A parallel arrangement allows current to flow from the battery through the circuit via multiple paths; in this case, flowing to both bulbs equally. Therefore, adding an extra bulb to the circuit will not affect the brightness of both bulbs. In a Series arrangement, current can only flow via a single path. In this case, adding an extra bulb to the circuit will split the current thoughout multiple bulbs, resulting in each bulb becoming dimmer as the number of bulbs increase.
Ans: Y: Parallel | Z: Series
b(ii) Explanation: This is pretty straightforward, and since we cannot do anything about the bulbs, we can add more current.
Ans: Anna can add more batteries to the circuit. This will make the electric current stronger, which means the bulbs will shine brighter.