A positively charged particle $$q$$ of mass $m$ is passed through a velocity selector. It moves horizontally rightward without deviation along the line $$y=\frac{2 m v}{q B}$$ with a speed $$v$$. The electric field is vertically downwards and magnetic field is into the plane of paper. Now, the electric field is switched off at $$t=0$$. The angular momentum of the charged particle about origin $$O$$ at $$t=\frac{\pi m}{q B}$$ is
The Curie temperature of cobalt and iron are $$1400 \mathrm{~K}$$ and $$1000 \mathrm{~K}$$ respectively. At $$T=1600 \mathrm{~K}$$, the ratio of magnetic susceptibility of cobalt to that of iron is
The torque acting on a magnetic dipole placed in uniform magnetic field is zero, when the angle between the dipole axis and the magnetic field is .........
The horizontal component of Earth's magnetic field at a place is $$3 \times 10^{-5} \mathrm{~T}$$. If the dip at that place is $$45^{\circ}$$, the resultant magnetic field at that place is