Question

The length of cylindrical metal (copper) is 1 cm and radius is 2.0 mm. If 120 V potential difference is applied across the ends of the rod then find out the electric current flowing through it. (Resistivity of copper is 1.7 × 10^-8 Ω-m)

Answer 1

Length (l) = 1 cm = 1 × 10^-2 m
Radius (r) = 2 mm = 2 × 10^-3 m
Area of cross section of wire
(A) = πr² = π ×(2 × 10^-3)² = 4π × 10^-6 m²
Potential across ends (V) = 120 V
Current (I) = ?
According to the Ohm’s law