Suppose you wish to construct a motor that produces a maximum torque whose magnitude is 1.7 * 10-2 N·m. The coil of the motor has an area of 9.0 * 10-4 m2, consists of N turns, and contains a current of 1.1 A. The coil is placed in a uniform magnetic field of magnitude 0.20 T. What must N be?

86 turns

Explanation:

Parameters given:

Magnetic torque, τ = 1.7 * 10^ (-2) Nm

Area of coil, A = 9 * 10^ (-4) m²

Current in coil, I = 1.1 A

Magnetic field, B = 0.2 T

The magnetic toque is given mathematically as:

τ = N * I * A * B

Where N = number of turns

To find the number of turns, we make N subject of formula:

N = τ / (I * A * B)

Therefore:

N = (1.7 * 10^ (-2)) / (1.1 * 9 * 10^ (-4) * 0.2)

N = 85.85 = 86 turns (whole number)

The number of turns must be 86.