Question

In a permanent magnet at room temperature

• A. Magnetic moment of each molecule is zero
• B. The individual molecules have non-zero magnetic moment which are all perfectly aligned
• C. Domains are partially aligned
• D. Domains are all perfectly aligned

Answer 1

The Correct Option is C

In a permanent magnet, at room temperature, the individual magnetic moments of the molecules are non-zero, but the domains (regions where magnetic moments are aligned) are not fully aligned. Some random thermal motion prevents the perfect alignment of the domains. This results in a net magnetic moment for the magnet, but not all the domains are perfectly aligned. Therefore, the correct answer is (C).

So, the correct answer is (C): Domains are partially aligned.

Answer 2

In a permanent magnet at room temperature, the individual magnetic domains (regions of uniform magnetization) have their magnetic moments aligned in a particular direction. However, due to thermal motion at room temperature, not all the domains are perfectly aligned.

• The magnetic moments of the individual molecules in each domain are non-zero, but due to the random thermal motion, the alignment of these domains is not perfect. As a result, the domains are only partially aligned.
• The alignment of these domains is the reason why a material can retain its magnetization and become a permanent magnet.

Therefore, the correct answer is (C) Domains are partially aligned.

Thus, the correct answer is (C).