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A capacitor of capacitance C charged by...

A capacitor of capacitance C charged by battery at V volt and then disconnected. At t = 0, it is connected to an uncharged capacitor of capacitance 2C through a resistance R. The charge on the second capacitor as a function of time is given by `q=(alpha CV)/(3) (1-e^(-(3t)/(beta RC)))` then fing the value of `(alpha )/(beta)`.

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To solve the problem, we need to analyze the given circuit and the charge transfer between the capacitors. Here’s a step-by-step solution: ### Step 1: Understand the Initial Conditions Initially, we have a capacitor of capacitance \( C \) charged to a voltage \( V \). The charge on this capacitor is given by: \[ Q_0 = CV \] This capacitor is then disconnected from the battery. ### Step 2: Connect the Capacitors At \( t = 0 \), the charged capacitor \( C \) is connected to an uncharged capacitor \( 2C \) through a resistor \( R \). The charge \( Q \) will flow from capacitor \( C \) to capacitor \( 2C \). ### Step 3: Charge Conservation The initial charge on capacitor \( C \) is \( CV \). When charge \( Q \) flows to capacitor \( 2C \), the remaining charge on capacitor \( C \) becomes: \[ Q_{\text{remaining}} = CV - Q \] ### Step 4: Voltage Across the Capacitors The voltage across capacitor \( C \) is: \[ V_C = \frac{Q_{\text{remaining}}}{C} = \frac{CV - Q}{C} = V - \frac{Q}{C} \] The voltage across capacitor \( 2C \) is: \[ V_{2C} = \frac{Q}{2C} \] ### Step 5: Apply Kirchhoff's Voltage Law According to Kirchhoff's law, the sum of the potential differences around the loop must equal zero: \[ V_C = V_{2C} + IR \] Substituting the expressions for \( V_C \) and \( V_{2C} \): \[ V - \frac{Q}{C} = \frac{Q}{2C} + IR \] Where \( I = -\frac{dQ}{dt} \). ### Step 6: Rearranging the Equation Rearranging gives: \[ V - \frac{Q}{C} - \frac{Q}{2C} = -R \frac{dQ}{dt} \] Combining terms: \[ V - \frac{3Q}{2C} = -R \frac{dQ}{dt} \] ### Step 7: Separate Variables Rearranging for separation of variables: \[ \frac{dQ}{\frac{2CV - 3Q}{2C}} = -\frac{dt}{R} \] ### Step 8: Integrate Integrating both sides: \[ \int \frac{2C}{2CV - 3Q} dQ = -\int \frac{dt}{R} \] This leads to: \[ \ln(2CV - 3Q) = -\frac{t}{R} + k \] Where \( k \) is the constant of integration. ### Step 9: Solve for \( Q \) Exponentiating both sides gives: \[ 2CV - 3Q = e^{-\frac{t}{R} + k} \] At \( t = 0 \), \( Q = 0 \): \[ 2CV = e^k \implies k = \ln(2CV) \] Thus: \[ 2CV - 3Q = 2CV e^{-\frac{t}{R}} \] Rearranging gives: \[ Q = \frac{2CV}{3}(1 - e^{-\frac{3t}{2RC}}) \] ### Step 10: Identify \( \alpha \) and \( \beta \) Comparing with the given function: \[ Q = \frac{\alpha CV}{3}(1 - e^{-\frac{3t}{\beta RC}}) \] We see that: - \( \alpha = 2 \) - \( \beta = 2 \) ### Step 11: Calculate \( \frac{\alpha}{\beta} \) Thus: \[ \frac{\alpha}{\beta} = \frac{2}{2} = 1 \] ### Final Answer The value of \( \frac{\alpha}{\beta} \) is \( 1 \). ---
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