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Moving Charges And Magnetism

Question
CBSEENPH12047882

Two long straight wires, each carrying an electric current of 5 A, are kept parallel to each other at a separation of 2.5 cm. Find the magnitude of the magnetic force experiment by 10 cm of a wire.

  • 4.0 × 10-4 N

  • 3.5 × 10-6 N

  • 2.0 × 10-5 N

  • 2.0 × 10-9 N

Solution

C.

2.0 × 10-5 N

The field at the site of one wire due to the other is

        B = μo i2πd

Where μo - permeability of free space

           i - current

         B  = 2 × 107 × 5.02.5 × 10-2

          B  =  4.0 × 10-5 T

The force experienced by 10 cm of this wire due to other is

       F = il B

           = (5.0 ) × ( 10 × 10-2 ) × ( 4.0 × 10-5 )

        F = 2.0 × 10-5 N