A very long, straight wire carries a steady current directed upward along the -axis.…
PHYSICS · Multi-part · CBSE · Physics · Magnetic Effects of Electric Current · Magnetic Effects of Electric Current
Problem
A very long, straight wire carries a steady current directed upward along the z-axis. Three small, identical magnetic-field probes are placed in the x–y plane at the following positions measured from the wire’s axis:
• Probe 1: r=0.10m
• Probe 2: r=0.20m
• Probe 3: r=0.30m
Answer the questions that follow. Assume the current remains constant throughout the experiment.
(a) Rank the magnitudes of the magnetic field detected by the three probes from greatest to least. Justify your ranking qualitatively without performing numerical calculations.
(b) Provide a verbal explanation, based on the functional dependence of the field on radial distance, for why the ranking in part (a) must hold.
(c) Suppose the current in the wire is doubled while the probes remain in place. Describe quantitatively (by what factor) and qualitatively how the magnetic‐field magnitude at each probe changes. Explain your reasoning.