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Through a coil of resistance R charge is...

Through a coil of resistance R charge is flowing in such a manner that in every time interval `t_(0)` the amount of charge flow is reduced by a factor of `1//2`. If a total of q charge flows through the coil in very long time, then the total amount of heat generated in the coil will be

A

`(1)/(4t_(0))q^(2)Rlog_(e)2`

B

`(3)/(2)(q^(2)Rlog_(e)2)/(t_(0))`

C

`(q^(2)Rlog_(e)2)/(2t_(0))`

D

`(3q^(2)Rlog_(e)2)/(4t_(0))`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem step by step, we will analyze the situation of charge flowing through a coil of resistance \( R \) and how it relates to the heat generated in the coil. ### Step 1: Understanding the Charge Flow We are given that the charge flowing through the coil reduces by a factor of \( \frac{1}{2} \) every time interval \( t_0 \). This indicates that the charge flow follows an exponential decay pattern, similar to radioactive decay. ### Step 2: Expressing Current as a Function of Time Since the charge reduces by half every \( t_0 \), we can express the current \( I(t) \) as: \[ I(t) = I_0 e^{-\lambda t} \] where \( \lambda = \frac{\ln 2}{t_0} \) and \( I_0 \) is the initial current. ### Step 3: Relating Charge and Current The total charge \( Q \) flowing through the coil can be expressed as: \[ Q = \int_0^{\infty} I(t) \, dt \] Substituting the expression for \( I(t) \): \[ Q = \int_0^{\infty} I_0 e^{-\lambda t} \, dt \] ### Step 4: Evaluating the Integral for Charge Evaluating the integral: \[ Q = I_0 \int_0^{\infty} e^{-\lambda t} \, dt = I_0 \left[ -\frac{1}{\lambda} e^{-\lambda t} \right]_0^{\infty} = I_0 \left( 0 + \frac{1}{\lambda} \right) = \frac{I_0}{\lambda} \] Thus, we have: \[ I_0 = Q \lambda \] ### Step 5: Heat Generated in the Coil The heat generated \( H \) in the coil can be calculated using: \[ H = \int_0^{\infty} I^2 R \, dt \] Substituting \( I(t) \): \[ H = \int_0^{\infty} (I_0 e^{-\lambda t})^2 R \, dt = R I_0^2 \int_0^{\infty} e^{-2\lambda t} \, dt \] ### Step 6: Evaluating the Integral for Heat Evaluating the integral: \[ H = R I_0^2 \left[ -\frac{1}{2\lambda} e^{-2\lambda t} \right]_0^{\infty} = R I_0^2 \left( 0 + \frac{1}{2\lambda} \right) = \frac{R I_0^2}{2\lambda} \] ### Step 7: Substituting \( I_0 \) in Terms of \( Q \) Now substituting \( I_0 = Q \lambda \): \[ H = \frac{R (Q \lambda)^2}{2\lambda} = \frac{Q^2 \lambda R}{2} \] ### Step 8: Replacing \( \lambda \) Since \( \lambda = \frac{\ln 2}{t_0} \): \[ H = \frac{Q^2 R \ln 2}{2 t_0} \] ### Final Answer Thus, the total amount of heat generated in the coil is: \[ H = \frac{Q^2 \ln 2}{2 t_0} R \]
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