\({f}\, = \frac{1}{{2\pi {m_a}RC}}\,\, = \,\,\frac{1}{{2\,\, \times 3.14\,\, \times \,\,0.6\,\, \times \,\,100\,\, \times \,\,{{10}^3}\,\, \times \,\,250\,\, \times \,\,{{10}^{ - 12}}}}\,\)
\(\, = \,\,0.0000106\,\, \times \,\,{10^9}\,\, = 10.6\,\,kHZ\)