The photograph shows a laptop computer plugged into the 230 V mains. (a) The laptop is left on standby. Its power consumption from the mains is 3.2 W. The cost of 1 kWh of electrical energy is 14 p. Calculate the cost of leaving the laptop on standby for 24 hours. (b) When the laptop is in normal use, its power consumption from the mains is 97 W. Calculate the current drawn from the mains.

GCSE Edexcel Physics Power: The photograph shows a laptop co

The photograph shows a laptop computer plugged into the 230 V mains - Edexcel - GCSE Physics - Question 3 - 2016 - Paper 1

Question 3

The photograph shows a laptop computer plugged into the 230 V mains. (a) The laptop is left on standby. Its power consumption from the mains is 3.2 W. The cost of... show full transcript

Worked Solution & Example Answer:The photograph shows a laptop computer plugged into the 230 V mains - Edexcel - GCSE Physics - Question 3 - 2016 - Paper 1

Step 1

Calculate the cost of leaving the laptop on standby for 24 hours.

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Answer

To find the cost, we follow these steps:

Convert Power Consumption to kW:
The power consumption is given as 3.2 W. To convert this to kilowatts (kW):
$3.2 ext{ W} = 0.0032 ext{ kW}$
Calculate Energy Used in kWh:
The energy consumed over 24 hours is:
$ext{Energy} = ext{Power} imes ext{Time} = 0.0032 ext{ kW} imes 24 ext{ hours} = 0.0768 ext{ kWh}$
Calculate the Cost:
The cost per kWh is 14 p. Therefore:
$ext{Cost} = ext{Energy} imes ext{Cost per unit} = 0.0768 ext{ kWh} imes 14 ext{ p} = 1.072 ext{ p}$
Rounding this to one decimal place, the total cost is approximately 1.1 p.

Step 2

Calculate the current drawn from the mains.

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Answer

To find the current drawn by the laptop, we can use the formula:
$I = rac{P}{V}$
where:

$I$ = current (in amperes, A)
$P$ = power (in watts, W)
$V$ = voltage (in volts, V)

Substitute the Known Values:
Given that the power consumption is 97 W and the voltage is 230 V, we have:
$I = rac{97}{230}$
Calculate the Current:
Doing the calculation gives:
$I = 0.4226 ext{ A}$ Rounding to two decimal places, the current drawn from the mains is approximately 0.42 A.

The photograph shows a laptop computer plugged into the 230 V mains - Edexcel - GCSE Physics - Question 3 - 2016 - Paper 1

Worked Solution & Example Answer:The photograph shows a laptop computer plugged into the 230 V mains - Edexcel - GCSE Physics - Question 3 - 2016 - Paper 1

Calculate the cost of leaving the laptop on standby for 24 hours.

Calculate the current drawn from the mains.

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