Question

In an electric motor, a circular coil with 84 turns of radius 3.9 cm can rotate between the poles of a magnet, as shown in the image below. When the current rhoguh the coil is 121 mA, the maximum torgue that the motor can deliver is 0.002 Nm. What is the magnitude of the magnetic field?

Answer 1

The magnitude of the magnetic field in the electric motor coil is approximately 0.0055 T.

Step-by-step explanation:

The magnitude of the magnetic field can be determined using the formula for torque in an electric motor. The formula is T = B * A * N * I * sinθ, where T is the torque, B is the magnetic field strength, A is the area of the coil, N is the number of turns, I is the current, and θ is the angle between the magnetic field and the normal to the plane of the coil. Rearranging the formula, we can solve for B as follows:

B = T / (A * N * I * sinθ)

Plugging in the given values: T = 0.002 Nm, A = π * (0.039 m)^2, N = 84, I = 0.121 A, and sinθ = 1 (since the angle is not specified), we can calculate:

B = 0.002 Nm / (π * (0.039 m)^2 * 84 * 0.121 A * 1)

B ≈ 0.0055 T