A student connects an electric fire to the mains supply. The power rating of the fire is 2.5 kW. (a) (i) Complete the sentence by putting a cross (✗) in the box next to your answer. A power of 2.5 kW is the same as: ☐ A 2500 amps per volt ☐ B 2500 joules per amp ☐ C 2500 joules per second ☐ D 2500 joules per volt (ii) 1 kWh of electricity costs 20p. Calculate the cost of keeping the fire on for 12 minutes.

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A student connects an electric fire to the mains supply - Edexcel - GCSE Physics - Question 3 - 2017 - Paper 1

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A student connects an electric fire to the mains supply. The power rating of the fire is 2.5 kW. (a) (i) Complete the sentence by putting a cross (✗) in the box ne... show full transcript

Worked Solution & Example Answer:A student connects an electric fire to the mains supply - Edexcel - GCSE Physics - Question 3 - 2017 - Paper 1

Step 1

Complete the sentence by putting a cross (✗) in the box next to your answer.

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Answer

The power rating of 2.5 kW can be expressed as 2500 joules per second. Thus, the correct answer is:

☐ A 2500 amps per volt ☐ B 2500 joules per amp ☑ C 2500 joules per second ☐ D 2500 joules per volt

Step 2

Calculate the cost of keeping the fire on for 12 minutes.

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Answer

To calculate the cost of keeping the fire on for 12 minutes:

Convert minutes to hours:

egin{align*} ext{Time in hours} = rac{12}{60} = 0.2 ext{ hours} ext{Cost} = ext{Power (kW)} imes ext{Time (h)} imes ext{Cost per kWh} ext{Cost} = 2.5 ext{ kW} imes 0.2 ext{ hours} imes 20 ext{ pence} ext{Cost} = 1 ext{ pound} = 100 ext{ pence} ext{Total cost} = 100 ext{ pence} ext{Total cost in pounds} = £1.00 ext{Cost of electricity} = 100 p

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