CGPSC Prelims General Studies 2025 Solved Paper 1

Concept:Dielectric constant is relative permittivity, a ratio of two permittivities, so it is dimensionless.Explanation:It is defined as $\varepsilon_r = \frac{\varepsilon}{\varepsilon_0}$.Here, $\varepsilon$ is the permittivity of the medium and $\varepsilon_0$ is the permittivity of free space.Both have the same units, so they cancel in the ratio.Therefore, $\varepsilon_r$ has no mass, length, or time dimension.Its dimensional formula is $M^0L^0T^0$.Answer:The dimension of dielectric constant is $M^0L^0T^0$.So, the correct option is A.