Consider two astronomical telescopes $T_1$ and $T_2$. $T_1$ has an objective of focal length $2 \mat

Question

Consider two astronomical telescopes $T_1$ and $T_2$. $T_1$ has an objective of focal length $2 \mathrm{~m}$ and diameter $1 \mathrm{~m}$. $T_2$ has an objective of focal length $1 \mathrm{~m}$ and diameter $2 \mathrm{~m}$. Assuming identical eyepieces, identify the correct statements.

Professor PC Thomas Classes · Answer

(a) : The resolving power of a telescope is directly proportional to the diameter of its objective lens ($	ext{RP} = \frac{D}{1.22\lambda}$). Since $D_2 = 2 \mathrm{~m} > D_1 = 1 \mathrm{~m}$, $T_2$ has higher resolving power. The angular magnification is proportional to the focal length of the objective ($M = f_o/f_e$). Since $f_{o1} = 2 \mathrm{~m} > f_{o2} = 1 \mathrm{~m}$, $T_1$ has higher magnifying power.