Two small spheres are immersed in a non-conducting oil whose relative permittivity…
PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
Two small spheres are immersed in a non-conducting oil whose relative permittivity (dielectric constant) is εr=2.2. Sphere X carries a charge of +4.8nC and sphere Y carries a charge of −7.2nC. The distance between the centers of the spheres is 6.0mm. The reference point of zero electric potential energy is taken at infinite separation.
Answer the following, showing all steps clearly and keeping track of units.
(a) Compute the electric potential energy of the two-sphere system in joules.
(b) Express the magnitude of the potential energy obtained in part (a) in electron-volts (eV). Use 1eV=1.60×10−19J.
(c) Comment on how the presence of the oil, compared to vacuum, affects the numerical value of the potential energy for the same charge magnitudes and separation.