A 1.0-μF capacitor is charged until it acquires a potential difference of 900.0 V. Across its plates,and then the emf source is removed.If the capacitor is then discharged through a 500.0-kΩ. Resistance,what is the voltage drop across the capacitor 9.0 ms. After beginning the discharge?
A)880 V
B)920 V
C)16 V
D)-16 V

Question

A 1.0-μF capacitor is charged until it acquires a potential difference of  900.0 V. Across its plates,and then the emf source is removed.If the capacitor is then discharged through a  500.0-kΩ. Resistance,what is the voltage drop across the capacitor 9.0 ms.  After beginning the discharge?
A)880 V
B)920 V
C)16 V
D)-16 V

Quizplus · Accepted Answer

The voltage across the capacitor as it discharges can be calculated using the formula for the discharge of a capacitor through a resistor: $V = V_0 e^{-\frac{t}{RC}}$, where $V_0$ is the initial voltage (900 V), $R$ is the resistance (500,000 Ω), $C$ is the capacitance (1.0 μF or $1.0 \times 10^{-6}$ F), and $t$ is the time (9.0 ms or $9.0 \times 10^{-3}$ s). Plugging in the values, we get $V = 900 e^{-\frac{9.0 \times 10^{-3}}{500,000 \times 1.0 \times 10^{-6}}}$. Calculating this gives a voltage close to 880 V, indicating that the capacitor still retains most of its initial charge after 9.0 ms.

A 10-μF Capacitor Is Charged Until It Acquires a Potential Difference