Question

A 200-turn rectangular coil having dimensions of 3.0 cm by 6.0 cm is placed in a uniform magnetic field of magnitude 0.76 T. (a) Find the current in the coil if the maximum torque exerted on it by the magnetic field is 0.14 N · m. A (b) Find the magnitude of the torque on the coil when the magnetic field makes an angle of 25° with the normal to the plane of the coil. N · m

Answer 1

here,

number of turns , N = 200 turns

area , A = 3 cm * 6 cm = 18 cm^2 = 18 * 10^-4 m^2

magnetic feild , B = 0.76 T

a)

let the current in the coil be I

maximum torque , Tm = N * I * A * B

0.14 = 200 * I * 18 * 10^-4 * 0.76

solving for I

I = 0.51 A

the current in the coil is 0.51 m

b)

theta = 25 degree

the magnitude of the torque on the coil when the magnetic field makes an angle of 25 degree with the normal to the plane of the coil , T = Tm * sin(theta)

T = 0.14 * sin(25) = 0.059 N.m