What is the magnetic force per unit length experienced by wire $C$ as shown in figure? (Assume that all wires are parallel and infinitely long).

A particle of charge $-q$ and mass $m$ enters a uniform magnetic field $\overrightarrow{B}$ at $A$ with speed $v_1$ at an angle $\alpha$ and leaves the field at $C$ with speed $v_2$ at an angle $\beta$ as shown. Then

A particle of charge per unit mass $\alpha$ is released from origin with a velocity $\overline{v}=v_0\hat{i}$ in a uniform magnetic field $\overline{B}=-B_0\hat{k}.$ If the particle passes through $(0, y, 0)$ then $y$ is equal to