The magnetic dipole moment $M$ of a bar magnet is the product of its pole strength $m$ and the magnetic length $2l$:
$$M = m \times (2l)$$Given values:
- Magnetic moment $M = 5.0\,\text{A}\cdot\text{m}^2$
- Distance between poles $2l = 20\,\text{cm} = 0.20\,\text{m}$Solving for pole strength $m$:
$$m = \frac{M}{2l} = \frac{5.0\,\text{A}\cdot\text{m}^2}{0.20\,\text{m}} = 25\,\text{A}\cdot\text{m}$$Hence, option 4 is the correct answer.
छड़ चुंबक का चुंबकीय द्विध्रुव आघूर्ण $M$ ध्रुव सामर्थ्य $m$ तथा चुंबकीय लंबाई $2l$ का गुणनफल होता है:
$$M = m \times (2l) \implies m = \frac{M}{2l}$$दिए गए मान:
$M = 5.0\,\text{A}\cdot\text{m}^2$ तथा $2l = 20\,\text{cm} = 0.20\,\text{m}$
ध्रुव सामर्थ्य: