A point charge of is placed in a medium of relative permittivity

PHYSICS · Single correct · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

A point charge of

+1\,\text{nC}

is placed in a medium of relative permittivity

\varepsilon_{r}=3

. The electric potential at a point in the medium is found to be

90\,\text{V}

. Find the distance of this point from the charge. (Take

\dfrac{1}{4\pi\epsilon_{0}}=9\times10^{9}\,\text{N m}^2\!\text{/C}^2

.) (a)

10\,\text{cm}

(b)

1.1\,\text{cm}

(c)

3.3\,\text{cm}

(d)

30\,\text{cm}