Question 7

Two long and parallel straight wires A and B carrying currents of 8.0 A and 5.0 A in the same direction are separated by a distance of 4.0 cm. Estimate the force on a 10 cm section of wire A.

Answer

Current flowing in wire A, I_{A} = 8.0 A

Current flowing in wire B, I_{B} = 5.0 A

Distance between the two wires, r = 4.0 cm = 0.04 m

Length of a section of wire A, l = 10 cm = 0.1 m

Force exerted on length l due to the magnetic field is given as:

Where,

µ_{0} = Permeability of free space = 4π × 10^{-7} T m A^{-1}

The magnitude of force is 2 × 10^{-5} N. This is an attractive force normal to A towards B because the direction of the currents in the wires is the same.

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