Question

A conductor of length 2 m carrying current 2 A is held parallel to an infinitely long conductor carrying current of 12 A at a distance of 100 mm, the force on small conductor is

• A. 8.6 × 10-5 N
• B. 6.6 × 10-5 N
• C. 7.6 × 10-5 N
• D. 9.6 × 10-5 N

Answer 1

Answer: (D)

9.6 × 10-5 N

Answer 2

Here $\mathrm { I } _ { 1 } = 2 \mathrm {~A} , \mathrm { I } _ { 2 } = 12 \mathrm {~A}$

$\mathrm { r } = 100 \mathrm {~mm} = 0.1 \mathrm {~m} , \mathrm { l } = 2 \mathrm {~m}$

The force per unit length on small conductor due to small long conductor

Now total force on length l of small conductor

$= \frac { 10 ^ { - 7 } \times 2 \times 2 \times 12 \times 2 } { 0.1 } = 9.60 \times 10 ^ { - 5 } \mathrm {~N}$