Two parallel beams of electrons moving in the same direction produce a mutual force

A circular current loop of radius a is placed in a radial field $B$ as shown. The net force acting on the loop is

Define Ampere from two current carrying parallel wires.

What is the magnitude of magnetic force per unit length (in $N \;m ^{-1}$) on a wire carrying a current of $8\; A$ and making an angle of $30^o$ with the direction of a uniform magnetic field of $0.15\;T$?

In figure shows three long straight wires $P, Q$ and $R$ carrying currents normal to the plane of the paper. All three currents have the same magnitude. Which arrow best shows the direction of the resultant force on the wire $P$

An elastic circular wire of length $l$ carries a current $I$. It is placed in a uniform magnetic field $\mathop B\limits^ \to $ (Out of paper) such that its plane is perpendicular to the direction of $\mathop B\limits^ \to $. The wire will experience