In an RC charging circuit, the graph of ln I versus t is a straight line shown dotted. If resistance is doubled, which solid line P, Q, R, S represents the new graph?
Select all that apply

Question

In an RC charging circuit, the graph of ln I versus t is a straight line shown dotted. If resistance is doubled, which solid line P,Q,R,S represents the new graph?

G1 Physics · Accepted Answer

For charging, I=(E/R)exp(−t/RC), so lnI=ln(E/R)−t/(RC). Doubling R lowers the intercept by ln2 and halves the magnitude of slope. Thus the new line starts lower and is less steep: curve Q. Correct answer: B.