$A$ straight horizontal long wire carries $30 \ A$ current. The linear mass density of the wire is $45 \ g/m$. What is the magnitude of the magnetic field needed to balance the wire in air?

Through two parallel wires $A$ and $B$,$10 \, A$ and $2 \, A$ of currents are passed respectively in opposite directions. If the wire $A$ is infinitely long and the length of the wire $B$ is $2 \, m$,the force on the conductor $B$,which is situated at a $10 \, cm$ distance from $A$,will be:

$A$ wire is bent as a parabolic curve and kept in the $x-y$ plane. The curve is described by the equation $x^2 = 6y$. The wire carries a current $i = 2 \ A$. If a uniform magnetic field $\vec{B} = 2 \times 10^{-3} \hat{k} \ T$ is applied,the force experienced by the wire is nearly: (in $hat{j} \ N$)

$A$ current-carrying wire $LN$ is bent as shown below. If the wire carries a current of $10 \, A$ and is placed in a magnetic field of $5 \, T$ which acts perpendicular to the paper outwards,then it will experience a force of ......... $N$.

If two streams of protons move parallel to each other in the same direction,then they

The magnetic field existing in a region is given by $\vec B = B_0 [1 + \frac{x}{l}] \hat k$. $A$ square loop of edge $l$ carrying current $I_0$ is placed with its edges parallel to the $x-y$ axes. Find the magnitude of the net magnetic force experienced by the loop.