focal length of eye lens, \(f_{e}=3.0 \,\mathrm{cm}\)
Magnifying power, \(M=?\)
Magnifying power of the Galilean telescope,
\(M_{D}=\frac{f_{0}}{f_{e}}\left(1-\frac{f_{e}}{D}\right)\)
\( = \frac{{30}}{3}\left( {1 - \frac{3}{{25}}} \right)\) \([\because D = 25\,{\text{cm}}]\)
\(=10 \times \frac{22}{25}=8.8\, \mathrm{cm}\)