Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Consider a ferromagnetic material : In the light of the above statements, choose the correct answer from the options given below :
- (A) is true but (R) is false
- Both (A) and (R) are true and (R) is the correct explanation of (A)
- (A) is false but (R) is true
- Both (A) and (R) are true but (R) is not the correct explanation of (A)
Answer
(4) Both (A) and (R) are true but (R) is not the correct explanation of (A)
Solution
As per NCERT, the individual atoms in a ferromagnetic material possess a dipole moment, and they interact with one another so that they spontaneously align in a common direction over a macroscopic volume called a domain. (A) is true.
As per NCERT, the ferromagnetic property depends on temperature: at high enough temperature the domain structure disintegrates and the material becomes paramagnetic; this transition temperature is the Curie temperature Tc. (R) is true.
(R) describes what happens at high temperature; it does not explain why domains form (that is due to the mutual interaction of the atomic dipoles).
Both are true but (R) is not the correct explanation of (A).
Answer: (4)