Question

If an object subtend angle of $2^{\circ }$ at eye when seen through telescope having objective and eyepiece of focal length $f_0=60cm$ and $f_e=5cm$ respectively then angle subtend by image at eye piece will be

• A. ${16}^{\circ }$
• B. ${50}^{\circ }$
• C. ${24}^{\circ }$
• D. ${10}^{\circ }$

Answer 1

The correct option is C ${24}^{\circ }$

By using $\frac{\beta }{\alpha }=\frac{f_0}{f_e}\Rightarrow \frac{\beta }{2^{\circ }}\Rightarrow \beta ={24}^{\circ }$