Capacitance

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1 mark

A capacitor is connected to a power supply and charged to a potential difference V₀.
The graph shows how the potential difference V across the capacitor varies with the charge Q on the capacitor.

q9-nov-2021-9ph0-01-edexcel-as-a-level-phy

At a potential difference V₀ a small charge ∆Q is added to the capacitor. This results in a small increase in potential difference ∆V across the capacitor.

Which of the following gives the approximate increase in energy stored on the capacitor due to this extra charge?

$∆ V \times ∆ Q$
$\frac{∆ V \times ∆ Q}{2}$
$V_{0} \times ∆ Q$
$\frac{V_{0} \times ∆ Q}{2}$

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1 mark

A capacitor of capacitance C is discharged through a resistor of resistance R.
The initial discharge current is $I_{0}$ .

Which of the following expressions gives the current after a time equal to RC?

$\frac{I_{0}}{e}$
$\frac{I_{0}}{2}$
$I_{0} e^{- R C}$
$I_{0} \ln \frac{1}{e}$

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Edexcel A Level Physics

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