A standard cell has an emf \(E\) of \(1.2\) volts. If the resistance \(R\) of the circuit is increasing at the rate of 0.03 ohm/sec, at what rate is the current (I) changing at the instant when the resistance is 6 ohms? Assume Ohm's Law E=IR Solution:
\(E = IR\)
\(1.2 = I (6)\)
\(I = 0.2~ amp\)
\(0 = I \frac{dR}{dt} + R \frac{dI}{dt}\), 0 since E is constant