Question

Compute the resistance in ohms of a copper block 5.0 cm long and 0.10 cm2 in cross-sectional area. (ρ = 1.77 × 10-6 ohm-cm)

Answer 1

R=ρ l/a
l=5 cm
a=0.10 cm²
ρ=1.77×10∧-6 Ωcm
R=(1.77×10∧-6) ×5/0.10
=8.85 ×10∧-5 Ω

resistance is directly proportional to length and inversly proportional to area of cross section is given by above equation