A long straight wire of diameter 0.5 mm carrying current 1 A is replaced by a wire of diameter 1 mm carrying the same current. How does the magnetic field at a distant point change?
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A long straight wire of diameter 0.5 mm carrying current 1 A is replaced by a wire of diameter 1 mm carrying the same current. How does the magnetic field at a distant point change?

G1 Physics · Accepted Answer

Step 1: Outside a long cylindrical wire, field B=μ₀I/(2πr) depends on enclosed current I and observation distance r. Step 2: Changing wire diameter but holding I and observation location outside fixed does not alter B. Step 3: The new and old field strengths are equal. Correct B. Final answer: (B) Same as the earlier value.