An electron is moving at a constant speed of 61 m/s on a circle of radius 3.8 m.

calculate the numerical value of i in a.

Charge on electron is 1.6x10^-19 Coulombs.In uniform circular motion v = r omega. omega = v/r. omega= 61/3.8 radians per second - cycle is 2pi radians. (61/3.8)x2pi cycles per second. A charge circulation rate of  (61/3.8)x2pix1.6x10^-19 Coulombs/second, or Amps. Which is a pretty small value of a current. Usually there many more electrons moving much faster, I think.