A student heated water in an electric kettle - AQA - GCSE Physics - Question 7 - 2020 - Paper 1
Question 7
A student heated water in an electric kettle.
Water has a high specific heat capacity.
Complete the sentence.
Choose answers from the box.
The specific heat capa... show full transcript
Worked Solution & Example Answer:A student heated water in an electric kettle - AQA - GCSE Physics - Question 7 - 2020 - Paper 1
Step 1
Complete the sentence.
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Answer
The specific heat capacity of a substance is the energy needed to raise the temperature of 1 kg of the substance by 1 °C.
Step 2
What is the correct symbol for a thermistor?
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Answer
The correct symbol for a thermistor is the one depicted as a circle with two leads connecting to it.
Step 3
Calculate the power of the heating element.
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Answer
Using the equation:
Power=Current2imesResistance
Further substituting the values:
Power=122imes15=144imes15=2160extW
Step 4
What is the reason for this?
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Answer
The heating element in the kettle takes time to heat up.
Step 5
Describe a method the student could have used to obtain the results shown in Figure 10.
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Answer
To obtain results similar to those shown in Figure 10, the student could follow these steps:
Measure the mass of water using a balance or measuring cylinder.
Measure the initial temperature of the water.
Pour the water into the kettle and insert a thermometer into the water.
Switch on the kettle and start recording the temperature at regular intervals (e.g., every 5 seconds) using a stopwatch to track the temperature rise over time.
Step 6
Calculate the energy transferred to the water.
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Answer
Using the formula:
E=mimescimesriangleT
Where:
m = mass of water = 0.50 kg
c = specific heat capacity = 4200 J/kg°C
ΔT = change in temperature = 100 °C - 20 °C = 80 °C
Substituting the values:
E=0.50imes4200imes80=168000extJ
Step 7
Calculate the energy transferred to change the water to steam.
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Answer
Using the formula:
E=mimesL
Where:
m = mass of water converted to steam = 5.0 g = 0.005 kg
L = specific latent heat of vaporization of water = 2260000 J/kg
