Ohm's Law and Wire Resistance

Steps:

• Current I = V/R from Ohm's law, with V constant in the circuit.
• Resistance R = ρ L / (π r²), where ρ is resistivity, L is length, r is radius.
• Increasing I requires decreasing R.
• Assess each option's impact on R.

Why B is correct:

• Increasing radius r increases cross-sectional area π r², decreasing R (inversely proportional to area per resistance formula), thus increasing I.

Why the others are wrong:

• A: Increasing length L increases R proportionally, decreasing I.
• C: Increasing resistance R directly decreases I.
• D: Increasing resistivity ρ increases R proportionally, decreasing I.

Final answer: B