Worksheet: Electric Potential of a Ring of Charge

In this worksheet, we will practice calculating the absolute electric potential at a given displacement from a ring of charge.


A uniformly charged ring of radius 10 cm is placed on a nonconducting table. It is found that, 3.0 cm above the centroid of the ring, the potential is 3.0 V, taking zero potential to be at infinity. How much charge is contained in the ring?

  • A2.3×10 C
  • B4.6×10 C
  • C6.2×10 C
  • D7.7×10 C
  • E3.5×10 C


A rod bent into the arc of a circle of radius 0.500 m subtends an angle 2𝜃 at the center 𝑃 of the circle as shown. Each 𝜃 equals 30. If the rod is charged uniformly with a total density 0.033 C/m, what is the magnitude of the electric field at 𝑃?

  • A63×10 N/C
  • B6.2×10 N/C
  • C69×10 N/C
  • D6.2×10 N/C
  • E9.2×10 N/C

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