Question

A simple telescope, consisting of an objective of focal length 60 cm and a single eye lens of focal length 5 cm is focussed on a distant object is such a way that parallel rays comes out from the eye lens. If the object subtends an angle 2⁰ at the objective, the angular width of the image –

• A. 10⁰
• B. 24⁰
• C. 50⁰
• D. 1/6⁰

Answer 1

Answer: (B)

24⁰

Answer 2

Since m =

m = $\frac { \text { Angle subtended by image } } { \text { Angle subended by the object } }$

= $\frac { \beta } { \alpha }$ Ž b = a × = = 24⁰