Question

A circular coil 17.1 cm in diameter and containing 11 loops lies flat on the gound. The Earth's magnetic field at this location has magnitude 5.5E-5 T and points into the Earth at an angle of 66.0 degrees below the horizontal line and aimed due north. Determine the torque if a 7.48 A clockwise current passes through the coil.

Answer 1

given that

magnitude of magnetic field B = 5.5 x 10⁻⁵T

diameter of coil = d = 17.1cm

=0.171 m

radius of the coil r = d/2

= 0.0855 m

area of the loop A = πr²

= ( 3.14 ) ( 0.0855 m)²

=0.0229 m²

(a) The angle between the normal to the coil and the field is 34.0°, so the torque is

q = 90 - 66 = 24°

t = N I A B sin q

= (11) (7.48 A) (0.0229 m²) (5.50 x 10⁻⁵T) sin 24.0°

= 4.215 x 10⁻⁵ N. m