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1. The problem statement, all variables and given/known data

The problem has been set up that a circuit containing a resistor and switch is being driven by a power source of unkown potential. The switch is flick to short the power source leaving only the resistor in a closed loop.

Calculate the current decay.

Initial current = 100A

Resistance = 1n[tex]\Omega[/tex]

2. Relevant equations

V=IR

Power = I^{2}R

3. The attempt at a solution

I'm not too sure. The power generated, and hence the heat loss can be found to be 1e-5W so thats 1e-5 Joules per second of heat loss.

I'm not sure if we have enough information. Current decay involving inductance or capacitance is well known but just a resistor in a circuit of 'ideal' conductors?

I'm assuming it is an exponential decay of form I=I_{0}e^{-t/[tex]\tau[/tex]}but finding the decay constant is proving tricky. Any advice????

Thanks in advance.

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# Homework Help: Finding time constant of current decay in closed circuit

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