The magnetic force depends on $\mathrm{v}$ which depends on the Inertial frame of reference. Does then the magnetic force differ from Inertial frame to frame? Is It reasonable that the net acceleration has a different value In different frames of reference?

Two long wires carrying current $I_1$ and $I_2$ are arranged as shown in figure. The one carrying current $I_1$ is along the $x$-axis. The other carrying current $I_2$ is along a line parallel to the $y$-axis given by $x=0$ and $z=d$. Find the force exerted at $O_2$ because of the wire along the $x$-axis.

A multirange voltmeter can be constructed by using a galvanometer circuit, as shown in figure. We want to construct a voltmeter that can measure $2 \mathrm{V}$, $20 \mathrm{V}$ and $200 \mathrm{V}$ using a galvanometer of resistance $10 \mathrm{\Omega }$ and that produces maximum deflection for current of $1 \mathrm{mA}$. Find $R_1$, $R_2$ and $R_3$ that have to be used.

A long straight wire carrying current of $25 \mathrm{A}$ rests on a table as shown in figure.  Another wire $PQ$ of length $1 \mathrm{m}$, mass $2.5 \mathrm{g}$ carries the same current but in the opposite direction. The wire $PQ$ is free to slide up and down. To what height will $PQ$ rise?