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Two capacitors C(1) = 2 mF and C(2) = 8 ...

Two capacitors `C_(1) = 2 mF and C_(2) = 8 mF` are seperately charged from the same battery. These two capacitors are then allowed to discharge separately through resistors of same resistance with a switch in series which are kept open initially. Both switches are closed at t = 0.

A

Current at t = 0 will be zero in both the capacitors.

B

At t = 0 current in `C_(1)` will be 4 times the current in `C_(2)`.

C

At t = 0 current in both the capacitors will be the same

D

Capacitor `C_(1)` loses 25% of its initial charge in lesser time than capacitor `C_(2)`.

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To solve the problem step by step, we will analyze the discharge of the capacitors and the relationships between their charge, current, and time constants. ### Step 1: Understand the Initial Conditions - We have two capacitors: - \( C_1 = 2 \, \text{mF} = 2 \times 10^{-3} \, \text{F} \) - \( C_2 = 8 \, \text{mF} = 8 \times 10^{-3} \, \text{F} \) - Both capacitors are charged from the same battery, so they have the same initial voltage \( V \). ### Step 2: Calculate the Initial Charge on Each Capacitor The charge \( Q \) on a capacitor is given by the formula: \[ Q = C \cdot V \] - For \( C_1 \): \[ Q_1 = C_1 \cdot V = 2 \times 10^{-3} \cdot V \] - For \( C_2 \): \[ Q_2 = C_2 \cdot V = 8 \times 10^{-3} \cdot V \] ### Step 3: Write the Discharge Equation The charge on a capacitor discharging through a resistor is given by: \[ Q(t) = Q_0 e^{-\frac{t}{RC}} \] Where: - \( Q_0 \) is the initial charge. - \( R \) is the resistance. - \( C \) is the capacitance. ### Step 4: Analyze the Current Flow The current \( I \) through the capacitor can be expressed as: \[ I(t) = -\frac{dQ}{dt} = \frac{Q_0}{R} e^{-\frac{t}{RC}} \] At \( t = 0 \): - The initial current \( I_0 \) for both capacitors is: \[ I_0 = \frac{V}{R} \] Since both capacitors are charged to the same voltage and have the same resistance, the initial current will be the same for both capacitors. ### Step 5: Compare Time Constants The time constant \( \tau \) for a capacitor is given by: \[ \tau = R \cdot C \] - For \( C_1 \): \[ \tau_1 = R \cdot C_1 = R \cdot 2 \times 10^{-3} \] - For \( C_2 \): \[ \tau_2 = R \cdot C_2 = R \cdot 8 \times 10^{-3} \] Since \( C_1 < C_2 \), we have \( \tau_1 < \tau_2 \). This means \( C_1 \) will discharge faster than \( C_2 \). ### Step 6: Determine Charge Loss To find out how long it takes for \( C_1 \) to lose 25% of its charge: - The final charge after losing 25%: \[ Q_f = Q_1 - 0.25 Q_1 = 0.75 Q_1 \] Using the discharge equation: \[ 0.75 Q_1 = Q_1 e^{-\frac{t}{\tau_1}} \] This simplifies to: \[ 0.75 = e^{-\frac{t}{\tau_1}} \] Taking the natural logarithm: \[ -\frac{t}{\tau_1} = \ln(0.75) \] Thus: \[ t = -\tau_1 \ln(0.75) \] ### Conclusion Since \( \tau_1 < \tau_2 \), \( C_1 \) will lose 25% of its charge in a shorter time than \( C_2 \).

To solve the problem step by step, we will analyze the discharge of the capacitors and the relationships between their charge, current, and time constants. ### Step 1: Understand the Initial Conditions - We have two capacitors: - \( C_1 = 2 \, \text{mF} = 2 \times 10^{-3} \, \text{F} \) - \( C_2 = 8 \, \text{mF} = 8 \times 10^{-3} \, \text{F} \) - Both capacitors are charged from the same battery, so they have the same initial voltage \( V \). ...
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