The resistance of a wire is 5 ohm. If its length is doubled and radius is halved, what is its new resistance?
Q1. The resistance of a wire is 5 ohm. If its length is doubled and radius is halved, what is its new resistance?
Answer: 40 ohm
Explanation: Using the formula R = ρ(L/A) and knowing that A is proportional to r^2, when L is doubled and r is halved, R becomes 8 times its original value, so R_new = 5 * 8 = 40 ohm. Option A is incorrect because it underestimates the change.