The hysteresis loop of a magnetic material has intercepts on the B -axis at 0.4 T and intercepts on the H -axis at 2500 A m ⁻¹ . A sample of this material is placed inside a solenoid of length 20 cm and 100 turns. The current required to be passed through the solenoid to completely demagnetize the sample is ________ A.

Step-by-step solution

The intercept on the H -axis of a hysteresis loop represents the coercivity of the material. Thus, the coercivity is H_c = 2500 A m ⁻¹ . The magnetic intensity H produced by the solenoid is given by H = ni , where n is the number of turns per unit length and i is the current. Given: N = 100 L = 20 cm = 0.2 m The turn density is n = N L = 100 0.2 = 500 m ⁻¹ . To demagnetize the sample, the magnetic intensity must equal the coercivity: H = H_c ni = 2500 500 i = 2500 i = 5 A. Answer: 5