Question

The following lists the length and diameter of three copper wires. Wire A

- 5 cm long, 10 mm thick; Wire B- 10 cm long, 5 mm thick; Wire C - 15 cm
long, 1 mm thick. Which of these wires most likely has the highest
resistance? Help i’m taking a test

Answer 1

Resistance is proportional to length and inversely proportional to area.

L1 = 5 cm

L2 = 10 cm

L3 = 15 cm

A1 = k * (.50 cm)^2

A2 = k * (.25 cm)^2 = 1/4 A1

A3 = k * (.05 cm)^2= 1/100 A1

R1 = 1 * 1 = 1

R2 = 2 * 4 = 8 R1

R3 = 3 * 100 = 300 R1

R3 has greatest resistance