- #1
ThLiOp
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Homework Statement
Derive the differential equation that relates the voltage (V) to the current (I) entering the circuit.
Homework Equations
Let:
ic = C dV/dt = current traveling through the capacitor (C)
ik = (V+Ek) / Rk = current traveling through the potassium (K) channel
iNa = (V-ENa) / RNa = current traveling through the sodium (Na) channel
iCl = (V+ECl) / RCl = current traveling thought the chlorine (Cl) channel
I = ic + ik + iNa + iCl = total current
The Attempt at a Solution
I = ic + ik + iNa + iCl
I = C dV/dt + (V+Ek) / Rk + (V-ENa) / RNa + (V+ECl) / RCl
My confusion is from the signs of the batteries. What is the convention (or physical meaning) when you are subtracting the voltages. For example, in the potassium (K) channel, it is V - (-Ek); while in the sodium (Na) channel, the signs on the battery are reversed. How do I know when a voltage source is positive or negative in relation to the current flow?
Thank you!