A copper wire of length 10   m and radius 10 - 2 π m has electrical resistance of 10 Ω . The current density in the wire for an electric field strength of 10   V   m - 1 is:

Step-by-step solution

Length = 10   m Radius = 10 - 2 π   m Electrical resistance = 10   Ω Electric field strength = 10   V   m - 1 Current density, J = I A = V R A = E L R A ⇒ J = 10 × 10 10 × π 10 - 2 π 2 = 10 5   A   m - 2