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1. Electric Charges and Fields
medium
An electron is moving round the nucleus of a hydrogen atom in a circular orbit of radius $r$. The coulomb force $\overrightarrow F $ between the two is (Where $K = \frac{1}{{4\pi {\varepsilon _0}}}$)
A
$ - K\frac{{{e^2}}}{{{r^3}}}\hat r$
B
$K\frac{{{e^2}}}{{{r^3}}}\vec r$
C
$ - K\frac{{{e^2}}}{{{r^3}}}\vec r$
D
$K\frac{{{e^2}}}{{{r^2}}}\hat r$
(AIPMT-2003)
Solution
$\overrightarrow {F\,} = – \,k\frac{{{e^2}}}{{{r^2}}}\hat r = – \,k.\frac{{{e^2}}}{{{r^3}}}\overrightarrow {r\,} $ $\left( {\,\,\hat r = \frac{{\overrightarrow {r\,} }}{r}} \right)$
Standard 12
Physics