The solar wind is a thin hot gas given off by the sun in all directions. Some of the charged particles enter the magnetic field of the Earth and can experience a magnetic force. Suppose some charged particles traveling at 9.0 x 105 m/s encounter the Earth's magnetic field at an angle of 90 where the magnitude of the field is 1.2 x 107 T. Find the radius of the circular path on which the particle would move it were (a) an electron and (b) a proton.