Question

In what way, Galileo telescope differs from an ordinary terrestrial telescope ?

Answer 1

in Galileo telescope , one convex lens and one concave lens are used while in ordinary terrestrial telescope, three convex lenses are used.

it is true that, magnifying power of object by Galileo telescope or magnifying power of object by terrestrial telescope, both are same.
because formula of magnification is $m=\frac{f_0}{f_e}$ for both telescopes .

but length of tubes are different for both telescopes.

for Galileo telescope, L = $f_0+f_e$
for terrestrial telescope, L = $f_0+f_e+4f$