(a) Wire resistance per metre = 3 ohm
As a result, the resistance of three 1.5 m long sections of this wire = 3 × 1.5 = 4.5 W
1 / R = 1 / 4.5 + 1 / 4.5 + 1 / 4.5
1 / R = 3 / 4.5
R = 1.5 ohm
(b) I = 2 A
V = IR
V = 2 × 4.5
V = 9 V
(c) For a 1 metre wire, R = 3 ohm
For a distance of 5 metres
R = 3 × 5
R = 15 ohm
Resistance is inversely proportional to area when the area is doubled, i.e. 2 A. As a result, resistance is reduced by half.
R = 15 / 2
R = 7.5 ohm