An electron having charge $1.6 \times 10^{-19} \ C$ and mass $9 \times 10^{-31} \ kg$ is moving with $4 \times 10^6 \ m \ s^{-1}$ speed in a magnetic field of $2 \times 10^{-1} \ T$ in a circular orbit. The force acting on the electron and the radius of the circular orbit is $.........$

• A
  $12.8 \times 10^{-13} \ N, 1.1 \times 10^{-4} \ m$
• B
  $1.28 \times 10^{-14} \ N, 1.1 \times 10^{-3} \ m$
• C
  $1.28 \times 10^{-13} \ N, 1.1 \times 10^{-3} \ m$
• D
  $1.28 \times 10^{-13} \ N, 1.1 \times 10^{-4} \ m$