A charged particle carrying charge $1 \mu C$ is moving with velocity $(2\hat{i}+3\hat{j}+4\hat{k}) \mathrm{m} {\mathrm{s}}^{-1}$. If an external magnetic field of $(5\hat{i}+3\hat{j}-6\hat{k})\times {10}^{-3}T$ exists in the region where the particle is moving then the force on the particle is $\overrightarrow{\mathrm{F}}\times {10}^{-9} \mathrm{N}$ . the vector $\overrightarrow{\mathrm{F}}$ is :

In the diagram shown, I₁, I₂ are the magnitude of current in the square loop and infinite long straight conductor respectively. The net magnetic field at the centre of loop is zero, then

In the figure shown, there are two semicircles of radii $r_1$ and $r_2$ in which a current $i$ is flowing. The magnetic induction at the Centre $O$ will be