COMEDK202510 May 2025Evening ShiftPhysicsMagnetic Effects of CurrentActual
A rectangular coil of length 10 cm and breadth 9 cm carries a current of 10 A . A long straight conductor carrying a current of 20 A is placed 1 cm from the coil parallel to its length and in the same plane of the coil. What will be the net force acting on the straight conductor?
Options
- A3.6 10⁻⁵ ~N
- B3.6 10⁻⁴ ~N
- C1.8 10⁻⁴ ~N
- D1.8 10⁻⁵ ~N
Correct answer
B. 3.6 10⁻⁴ ~N
Step-by-step solution
Forces on the breadth arms cancel. Net force is the difference between forces on the two length arms ( L = 0.1 m). Force formula: F = ₀ I₁ I₂ L 2 r Nearer arm at r₁ = 1 cm = 0.01 m: F₁ = 2 10⁻⁷ 20 10 0.1 0.01 = 2 10⁻⁷ 200 0.1 0.01 = 4 10⁻⁴ N Farther arm at r₂ = 1 + 9 = 10 cm = 0.1 m: F₂ = 2 10⁻⁷ 20 10 0.1 0.1 = 0.4 10⁻⁴ N F_ net = F₁ - F₂ = 4 10⁻⁴ - 0.4 10⁻⁴ = 3.6 10⁻⁴ N