$A$ conducting rod of mass $m$ and length $l$ is free to move without friction on two parallel long conducting rails,as shown in the figure. There is a resistance $R$ across the rails. In the entire space,there is a uniform magnetic field $B$ normal to the plane of the rod and rails. The rod is given an impulsive velocity $v_0$. What happens to the initial kinetic energy $\frac{1}{2} m v_0^2$?

• A
  It will be converted fully into heat energy in the resistor.
• B
  It will enable the rod to continue to move with velocity $v_0$,since the rails are frictionless.
• C
  It will be converted fully into magnetic energy due to induced current.
• D
  It will be converted into the work done against the magnetic field.