Mains electricity is rated 230 V in the UK - AQA - A-Level Physics - Question 23 - 2021 - Paper 2
Question 23
Mains electricity is rated 230 V in the UK.
Which is correct?
A The mean voltage is 163 V.
B The peak voltage is 230 V.
C The root mean square voltage is 325 V.
D T... show full transcript
Worked Solution & Example Answer:Mains electricity is rated 230 V in the UK - AQA - A-Level Physics - Question 23 - 2021 - Paper 2
Step 1
A The mean voltage is 163 V.
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Answer
The mean voltage in an AC circuit is typically different from the root mean square (RMS) voltage. In a sinusoidal waveform, the mean voltage is approximately 0.637 times the peak voltage, which does not equate to 163 V.
Step 2
B The peak voltage is 230 V.
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Answer
In an AC circuit, the RMS voltage (230 V) is related to peak voltage (V_peak) by the formula:
oot{2}
ightarrow V_{peak} = 230V imes
oot{2} \\ = 230V imes 1.414 \\ = 325.5 V.$$
Thus, the peak voltage is not 230 V.
Step 3
C The root mean square voltage is 325 V.
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Answer
The RMS voltage for mains electricity is indeed 230 V, and from the calculation above, we find that the RMS voltage is not equivalent to 325 V, making this statement false.
Step 4
D The peak-to-peak voltage is 650 V.
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Answer
The peak-to-peak voltage ( ext{V}_{pp}) is calculated as:
Vpp=2imesVpeak=2imes325.5V=651V.
Thus, this statement is correct, as it approximates to 650 V.
