The relative magnetic permeability of diamagnetic substances is always:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → less than 1
The relative permeability is \( \mu_r = 1 + \chi \), where \( \chi \) is the magnetic susceptibility. A diamagnetic substance has a small negative susceptibility, \( -1 \le \chi \lt 0 \), so \( \mu_r \) is slightly less than 1 and the field inside the material is slightly reduced.
NCERT (2026-27):
Magnetic Properties of Materials – …
