Question

In deflection magnetometer, to find dipole moment $M$ of a magnet, angle of deflection should be

• A. $0^0$
• B. ${90}^0$
• C. ${45}^0$
• D. any angle

Answer 1

The correct option is C ${45}^0$

In deflection magnetometer, $\frac{{\mu }_o}{4\pi }\frac{2M}{d^3}=Htan\theta$

Thus for $\theta =0⟹M=0$ (always) and for $\theta =90⟹tan{90}^o=\infty$

Thus for proper working of instrument, $\theta$ should be ${45}^o$ as $tan{45}^o=1$