A conducting rod, with a resistor of resistance $R,$ is pulled with constant speed $v$ on a smooth conducting rail as shown in figure. A constant magnetic field $\overrightarrow{B}$ is directed into the page. If the speed of the bar is doubled, by what factor does the rate of heat dissipation across the resistance $R$ change?

• A

  $0$
• B

  $\sqrt{2}$
• C

  $2$
• Correct answer
  D

  $4$

Hence, the correct answer is option: 'D'.