Problem Sheet 8

The numbers in square brackets refer to the number of the problem in your textbook.

- [E15.4] A magnetic element has two unpaired electrons and an exchange interaction that causes them to align such that their magnetic fields are parallel. Its atomic volume , $\Omega$, is 3.7 x 10
^{-29}m^{3}. What would you expect its saturation magnetization, M_{s}, to be? - [E15.5] A coil of turns and length 10 mm carries a current of 0.01 amps. The core of the coil is made of a material with a susceptibility $\chi = 10^4$. What is the magnetization M and the induction B?
- A transformer core is wound with a coil carrying an alternating current at a frequency of 50 Hz. Assuming the magnetization to be uniform throughout the core volume of 0.01 m
^{3}, calculate the hysteresis loss. The hysteresis loop has an area of 60000 units, when the axes are drawn in units of 10^{-4}Wb m^{-2}and 10^{2}A m^{-1}. - In a 440 V, 50 Hz transformer, the total iron loss is 2300 W. When the applied voltage is 220 V at 25 Hz, the total iron loss is 750 W. What is the contribution of the eddy current losses in both these cases? What is the hysteresis loss at 50 Hz?

page revision: 0, last edited: 03 Mar 2009 06:48