AIIMS 2017 Physics Telescopes MCQ Question

In a simple telescope, the angular width of the image can be calculated using the formula $\theta = \frac{h}{f}$, where $h$ is the height of the object and $f$ is the focal length of the objective lens. For an objective with a focal length of 60 cm and an eye lens of 5 cm, the total angular width subtended by the image at the eye lens is $2 \times \tan^{-1}\left(\frac{h}{2f}\right)$. Given that the object subtends an angle of 10° at the objective, this angle remains unchanged when viewed through the eyepiece, confirming option A as correct.

Options B (24°), C (50°), and D (1/6°) do not align with the principles of angular magnification in telescopes, where the angle subtended by the image at the eye lens is equal to the angle subtended by the object at the objective for distant objects.