If a long hollow copper pipe carries a current, then magnetic field is produced:

Question

G1 Physics · Accepted Answer

Step 1: Inside the empty bore of a hollow cylindrical conductor, Ampère's loop encloses no net axial current (ideal symmetric distribution). Step 2: Therefore B(inside)(2πr)=μ₀×0⇒B(inside)=0. Step 3: Outside, enclosed current is I and B(outside)=μ₀I/(2πr). Thus field exists outside the pipe only. B. Final answer: (B) outside the pipe only.