Final answer:
The potential near the surface of a 0.390 cm diameter plastic sphere with a uniformly distributed 20.0 pC static charge is approximately 9200 volts.
Step-by-step explanation:
Calculating Electric Potential of a Static Charge
A plastic sphere used in a static electricity demonstration has a diameter of 0.390 cm and carries a uniformly distributed charge of 20.0 pC on its surface. To find the potential near its surface, we use the formula for the potential (V) of a sphere with uniformly distributed charge, which is:
V = (k * Q) / r
Where:
Q is the charge on the sphere (20.0 pC or 20.0 x 10-12 C).
r is the radius of the sphere, half of the diameter (0.390 cm / 2 = 0.195 cm or 0.195 x 10-2 m).
Substituting the given values into the equation:
V = (8.988 x 109 * 20.0 x 10-12) / (0.195 x 10-2)
Calculating the potential, we get:
V ≈ 9200 V
Therefore, the potential near the surface of the sphere is approximately 9200 volts.