Question Detail
Question
A coil has 45 turns and an area of 1.8 x 10⁻² m². If the torque on the coil is 2.5 x 10⁻² Nm when placed in a magnetic field of 0.08T, calculate the current flowing in the coil.
Correct Answer
Option B is the correct answer.
Detailed Explanation
The maximum torque (τ) on a current-carrying coil in a magnetic field is given by the formula τ = NIAB, where:N = number of turns = 45I = current (what we need to find)A = area of the coil = 1.8 × 10⁻² m²B = magnetic field strength = 0.08 TRearranging the formula to solve for I:I = τ / (NAB)I = (2.5 × 10⁻² Nm) / (45 × 1.8 × 10⁻² m² × 0.08 T)I = 2.5 / (45 × 1.8 × 0.08) AI = 2.5 / 6.48 AI ≈ 0.3858 ARounding to two decimal places, the current is approximately 0.39 A.
Hint
Use the formula for torque on a current loop in a magnetic field (τ = NIAB) and solve for current.