Question

An example for a soft magnet is given as,
A. 45 Permalloy
B. $Cr{{O}_{2}}$
C. $Fe-Pd$
D. alnico

Answer 1

Hint: Soft magnets are magnetic material which can be easily magnetised as well as very easily demagnetised. Their prime use is that they can increase or enhance the flux created by an electric current. Permalloy is a term for nickel iron magnetic alloy. Alloys containing less iron, nickel or cobalt are found to be magnetically soft and have a weaker magnetic field. These all details will help you to solve this question.

Complete step-by-step answer:
Materials which can be magnetised for temporarily only are called magnetically soft. The general soft magnetic materials are given as iron, iron-silicon alloys, and the nickel-iron alloys. There is a small magnetic anisotropy which is the barrier in switching the magnetisation for this type of magnets. This has been there in order to reduce the hysteretic losses and enhance the permeability. Irons are commonly used for their magnetic characteristics because of their relatively cheap rate. There are mainly six kinds of nickel-irons which are often called permeability alloys. These are having high usage in the magnetic field. These soft irons are commonly used for fabricating the thin pieces which are laminated to become transformer cores. From this we can understand that the 45 permalloy is the soft magnet in the options given.

So, the correct answer is “Option A”.

Note: The types of applications for the soft magnetic materials is divided into two prime categories. In direct current usage, the substance has been magnetised in order to do an operation and at the end of the operation they will get demagnetised. In alternative current usage the substance will be continuously varied from magnetised condition to the demagnetised one in each cycle throughout the operation period.