Hysteresis loops for two magnetic materials A and B are given below :
These materials are used to make magnets for electric generators, transformer core and electromagnet core. Then it is proper to use :AB
(A)A for electromagnets and B for electric generators
(B)A for transformers and B for electric generators
(C)B for electromagnets and transformers✓ Correct
(D)A for electric generators and transformers
Answer: (C)
Solution
For a core that is magnetised and demagnetised again and again, as in a transformer or an electromagnet, the energy lost per cycle is the area of the hysteresis loop, so you want a thin loop with low coercivity. Material B has the narrower loop and lower coercivity, so it suits both electromagnets and transformers, while the wide-loop, high-coercivity material A is better reserved for permanent magnets. The proper choice is to use B for electromagnets and transformers.
JEE Main · 2016 · 03 Apr 2016 · Offline · Single correct option
