A man monitors how much money he spends on electricity - Edexcel - GCSE Physics - Question 6 - 2015 - Paper 1
Question 6
A man monitors how much money he spends on electricity.
He uses a device which calculates the cost of electrical energy used.
He connects his 2.9 kW electric kettle ... show full transcript
Worked Solution & Example Answer:A man monitors how much money he spends on electricity - Edexcel - GCSE Physics - Question 6 - 2015 - Paper 1
Step 1
Calculate the current in the kettle element.
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Answer
To calculate the current, we use the formula:
I=VP
where:
I = Current (in Amperes)
P = Power (in Watts)
V = Voltage (in Volts)
Substituting the known values:
I=230 V2900 W
Calculating further gives:
I=12.61 A
Step 2
Calculate the length of time for which the kettle has been switched on during the week.
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Answer
First, we need to find out how much electrical energy the kettle used in kWh:
The total cost is 97 p.
The cost of 1 kWh is 17 p.
To find the total energy used in kWh, we divide:
Total energy (kWh)=17 p/kWh97 p=5.71 kWh
Next, using the power of the kettle (2.9 kW), we can calculate the time:
Time (hours)=Power (kW)Energy (kWh)=2.9 kW5.71 kWh=1.97 hours
Therefore, the kettle has been switched on for approximately 1.97 hours during the week.
