A proton is accelerated from rest through 2.0 kV. It then enters a uniform magnetic field of 0.30 T that is oriented perpendicular to its direction of motion. Required:
a. What is the radius of the path the proton follows in the magnetic field?
b. How long does it take the proton to make one complete circle in the magnetic field?

the answer is 46 mls because when you add the speed per second it increses the speed

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.