A1.0-mm-diameter ball bearing has 2.0 * 109 excess electrons. what is the ball bearing's potential?

Bearing potential of Ball= 5760 V

Explanation:

the electric potential is given by

Q= electrostatic constant= 9 x 10⁹ Nm²/C

Q= charge= n e

n= number of electrons= 2 x 10⁹

e= charge of electron=-1.6 x 10⁻¹⁹ C

so Q=2 x 10⁹ (-1.6 x 10⁻¹⁹ )

Q= -3. 2 x 10⁻¹⁰ C

r= radius of sphere=1/2 mm= 0.0005 m

V= 5760 volt

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.