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The circuit shown is used to charge and then discharge a capacitor C - Scottish Highers Physics - Question 19 - 2018
Question 19
The circuit shown is used to charge and then discharge a capacitor C. Which pair of graphs shows how the potential difference V across the capacitor varies with tim... show full transcript
Worked Solution & Example Answer:The circuit shown is used to charge and then discharge a capacitor C - Scottish Highers Physics - Question 19 - 2018
Step 1
Charging
Answer
During the charging process, the potential difference V across the capacitor increases exponentially as it approaches the supply voltage. This behavior can be described by the equation:
where is the maximum potential difference (supply voltage), R is the resistance, and C is the capacitance.
This means that the graph of V against t during charging will start from 0 and rise asymptotically towards . In the options provided, only graph E represents this charging curve correctly.
Step 2
Discharging
Answer
During the discharging phase, the potential difference V decreases exponentially as the capacitor releases its stored energy. This can be described by the equation:
where is the initial potential difference across the capacitor at the start of discharging. Thus, the potential difference will start at and decrease towards 0. Again, only graph E accurately reflects this behavior for discharging.