The power in watts for a circuit is given by P = I ²R. How fast is the power changing if the resistance, R, of the circuit is 1,400 $\Omega$, the current, I, is 1.5A, and the current is decreasing with respect to time at a rate of 0.025 A/s. (Assume R is a constant.) A) 105 w/s B) 4,200 w/s C) 26.25 w/s D) 157.5 w/s E) -105 w/s

Question

Quizplus · Accepted Answer

Given P = I^2R, differentiate both sides with respect to time (t) to find dP/dt = 2IR(dI/dt). Substituting the given values: dP/dt = 2 * 1400 * 1.5 * (-0.025) = -105 W/s. The negative sign indicates power is decreasing.

The Power in Watts for a Circuit Is Given by P