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 Current: 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 of leaving the laptop on standby, we start by converting the power consumption from watts to kilowatts:

$3.2 ext{ W} = 0.0032 ext{ kW}$

Next, we calculate the energy consumed in 24 hours:

$ext{Energy (kWh)} = ext{Power (kW)} imes ext{Time (h)} = 0.0032 ext{ kW} imes 24 ext{ h} = 0.0768 ext{ kWh}$

Now, we can calculate the cost of this energy usage:

$ext{Cost} = ext{Energy (kWh)} imes ext{Cost per kWh} = 0.0768 ext{ kWh} imes 14 ext{ p} = 1.0752 ext{ p}$

Rounding to one decimal place, the cost is approximately 1.1 p.

Step 2

Calculate the current drawn from the mains.

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Answer

To calculate the current drawn from the mains, we use the formula:

$P = V imes I$

where:

$P$ is the power (in watts),
$V$ is the voltage (in volts),
$I$ is the current (in amperes).

Substituting the known values:

$97 ext{ W} = 230 ext{ V} imes I$

We rearrange to find $I$ :

$I = rac{P}{V} = rac{97 ext{ W}}{230 ext{ V}} \\I = 0.4217 ext{ A}$

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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