A long horizontal wire $$\mathrm{P}$$ carries current of $$50 \mathrm{~A}$$ from left to right. It is rigidly fixed. Another fine wire $$\mathrm{Q}$$ is placed directly above and parallel to $$\mathrm{P}$$. The mass of the wire is '$$\mathrm{m}$$' $$\mathrm{kg}$$ and carries a current of '$$\mathrm{I}$$' A. The direction of current in $$\mathrm{Q}$$ and position of wire $$\mathrm{Q}$$ from $$\mathrm{P}$$ so that the wire $$\mathrm{Q}$$ remains suspended are

A charge of $$+1 \mathrm{C}$$ is moving with velocity $$\vec{V}=(2 \mathrm{i}+2 \mathrm{j}-\mathrm{k}) \mathrm{ms}^{-1}$$ through a region in which electric field $$\vec{E}=(\mathrm{i}+\mathrm{j}-3 \mathrm{k}) \quad \mathrm{NC}^{-1}$$ and magnetic field $$\vec{B}=(\mathrm{i}-2 \mathrm{j}+3 \mathrm{k}) \mathrm{T}$$ are present. The force experienced by the charge is

To increase the current sensitivity of a moving coil galvanometer by $$25 \%$$, its resistance is increased so that the new resistance becomes twice its initial resistance. By what factor does the voltage sensitivity change?

Current flows through uniform, square frames as shown in the figure. In which case is the magnetic field at the centre of the frame not zero?