Physics Assignment, UOW, Malaysia When a capacitor is charged through a resistor by a constant voltage source, the voltages across the capacitor

Part 1: Charging a Capacitor

Equipment:

• Power supply
• One large capacitor (about 2500µF), Resistance box
• Multimeter
• 4 banana cables
• Stopwatch

When a capacitor is charged through a resistor by a constant voltage source, the voltages across the capacitor and resistor change exponentially with time. That is,

Where V is the applied voltage.

Likewise, when a capacitor is discharged through a resistor, the voltage is given by

Where V₀ is the initial voltage across the capacitor.

The rate at which the capacitor charges or discharges can be characterized by the time constant RC. When charging, RC is the time that it takes for the capacitor voltage to increase from zero voltage to 0.632 times the charging voltage, since at t=RC

Similarly, when discharging, RC is the time for the voltage to fall to 0.368 times its initial value, since at t=RC

RC Circuits

1. When a capacitor is charged through a resistor by a constant voltage source, what are the voltages across the capacitor and a resistor?
2. When a capacitor is discharged through a resistor by a constant voltage source, what are the voltages across the capacitor and a resistor?

Answer

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