A steady current I is set up in a wire whose cross-sectional area decreases in the direction of the flow of the current. Then, as we examine the narrowing region,

Step-by-step solution

When current flows through a conductor of tapered cross-section, current flow through every section remains constant. ⇒ I 1 = I 2 ⇒ j 1 A 1 = j 2 A 2 ⇒ j 1 j 2 = A 2 A 1 1 ⇒ j 1 j 2 Current density increases in the narrow region. Also, = n e v d ⇒ n e v d 1 n e v d 2 ⇒ v d 1 v d 2 Drift velocity increases in the narrow region. and j = E ρ where, ρ = resistivity of material. ⇒ E 1 ρ E 2 ρ ⇒ E 1 E 2 Electric field magnitude increases in the narrow region.