Two identical point charges experience a force of when placed apart in air

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

Problem

Two identical point charges experience a force of

0.50\,\text{N}

when placed

6\,\text{cm}

apart in air. The same charges are now separated by

2\,\text{cm}

in a dielectric oil with relative permittivity

\varepsilon_r = 5

. What is the new force between them? (a)

1.5\,\text{N}

(b)

0.20\,\text{N}

(c)

0.90\,\text{N}

(d)

4.5\,\text{N}