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Two parallel, long wires are kept 0.20 m apart in vacuum, each carrying a current of x A in the same direction. If the force of attraction per metre of each wire is 2×10⁻⁶ N, then the value of x is approximately

Asked in JEE Main 28th June 2nd Shift 2022 · Force between parallel currents

• (1) 1
• (2) 2.4
• (3) 1.4
• (4) 2

Step-by-step solution

Why the other options are wrong

• (1) Takes the separation as 0.1 m (half the gap), which gives x²=1.
• (2) Takes the square root of the wrong power of ten.
• (4) Uses (μ₀)/(4π d) in place of (μ₀)/(2π d), which gives x²=4.

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