Physics · Oct / Nov 2025 · Paper 61 · Question 4

0625

As printed in the paper

The question as text

0625/61/O/N/25 © UCLES 2025 4 A student is investigating electrical heaters that are used in the school laboratory to heat beakers of water. The heaters are all 12 V heaters with the same power rating. The student thinks that some heaters are more efficient than other heaters. Plan an experiment to compare how quickly the heaters increase the temperature of water to boiling point. The following apparatus is available to the student: • five electrical heaters • beakers • supply of water • 12 V power supply with suitable leads. Other apparatus normally available in a school laboratory can also be used. In your plan: • list any additional apparatus required • explain briefly how you do the investigation, including the measurements you take • state the key variables to be kept constant • draw a suitable table, with column headings, to show how to display your readings (you are not required to enter any readings in the table) • explain how you use the results to reach a conclusion.

Read automatically from the paper; the printed page above is exact.

Show the answer and mark scheme

MP1

APPARATUS: A suitable timer

AND a thermometer (so same initial temp.)

MP2

MEASURE time taken to heat water to boiling point

MP3

INVESTIGATION: Repeat a correct investigation for other heaters

MP4

TWO VARIABLES TO KEEP CONSTANT:

Initial temperature of water

MP5

Volume / mass / amount of water

MP6

TABLE with clear columns for heater and time with unit.

MP7

CONCLUSION:

Construct a bar chart with heater against heating time

OR compare times for each heater to see if / how / whether the heater affects the time (to reach b.p.). OR see if the differences are significant / large / beyond experimental accuracy or wtte.

Please put ticks / crosses by the side of the response in the order of the marking points.

Each marking point should be judged independently: if the correct answer is seen, the mark is awarded. If a wrong investigation is described, an ECF should be applied only for MP6 and MP7 (the table and conclusion).

A few candidates answer Q4 with a series of bullet points which may correspond to the bullet points in the question. Be aware of this. Thus the third bullet point of the response might say merely ‘Volume of water’. That then scores MP5.

Q2.

Additional graph notes:

NOTE: The principle to apply here is ‘could I draw a significantly better line, using these points, under examination conditions?’ If the answer is definitely ‘yes’, do not award the mark.

NOTE: –

If candidate’s scale consists of actual readings at equal intervals this will produce a perfect straight line! The only marks available in this case are the first (axes right way round and labelled). So maximum 1.

If axes are wrong way round, the other 3 marks are still available.

Guidance on significant figures.

Some questions are intended to assess this, and give the number of figures which are acceptable in the final answer.

Where the mark scheme does not mention them, accept any number of significant figures from two upwards so long as the answer rounds to the value in the mark scheme. This includes recurring notation.

Guidance on rounding errors.

A rounding error in an answer should be penalised, but only where it occurs within one of the first three figures. Beyond that it may be ignored.

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