A small object carries a charge of 10.0 μC.If the object is so small that it can be regarded as a point charge,what is the energy density at a distance of 2.0 m from the charge? (The value of k is 9.0 $\times$ 10⁹ N·m²/C². )

Question

Quizplus · Accepted Answer

The energy density (u) of an electric field is given by u = (1/2)ε₀E², where E is the electric field. The electric field E due to a point charge is E = kQ/r². Substituting the given values, E = (9.0 x 10⁹ N·m²/C²)(10.0 x 10⁻⁶ C)/(2.0 m)² = 22,500 N/C. Then, u = (1/2)(8.85 x 10⁻¹² C²/N·m²)(22,500 N/C)² = 2.2 mJ/m³.

A Small Object Carries a Charge of 10 ×\times× 109 N·m2/C2

A Small Object Carries a Charge of 10 $\times$ 10⁹ N·m²/C²