A silver wire has resistivity of 1.62 ×10⁻⁸ Ωm and a cross-sectional area of 5.00 mm². The current in the wire is uniform and changing at the rate of 2000 A/s when the current is 100 A.
Select all that apply

Question

A silver wire has resistivity of 1.62 ×10⁻⁸ Ωm and a cross-sectional area of 5.00 mm². The current in the wire is uniform and changing at the rate of 2000 A/s when the current is 100 A.

G1 Physics · Accepted Answer

The electric field in the wire is E=ρI/A=(1.62×10⁻⁸)(100)/(5×10⁻⁶)=0.324 V m⁻¹, so A is true. dE/dt=(ρ/A)(dI/dt)=6.48 V m⁻¹ s⁻¹. Thus Iᴅ=ε₀A(dE/dt)≈2.87×10⁻¹⁶ A, so B is true. The magnetic-field ratio at the same radius equals Iᴅ/I≈2.87×10⁻¹⁸, so C is true. D is false. Correct: A,B,C.