Q. The mass of a specimen of a ferromagnetic material is 0.6kg and its density is 7.8 × 10³ kg/m³. If the area of hysteresis loop of alternating magnetising field of frequency 50Hz is 0.722 MKS units then the hysteresis loss per second will be

(a) 277.7 × 10^{-5} Joule

(b) 277.7 × 10^{-6} Joule

(c) 277.7 × 10^{-4} Joule

(d) 277.7 × 10^{-3} Joule

Ans: (a)

Energy Loss per sec

$ \displaystyle = \nu A V t $

$ \displaystyle = \nu \times A \times \frac{m}{\rho} t $

$ \displaystyle = 50 \times 0.722 \times \frac{0.6}{7.8 \times 10^3} \times 1 $

= 277.7 × 10^{-5} Joule