Question

A simple telescope consisting of an objective lens of focal length 30 cm and that of its eye-lens is 3 cm. It is focused on a scale 2 metres distant from it. The distance of objective lens from eye-lens to see with relaxed eye is -

• A. 33 cm
• B. 65.3 cm
• C. 38.3 cm
• D. 40.3 cm

Answer 1

Answer: (C)

38.3 cm

Answer 2

u₀ = - 200 cm; f₀ = 30 cm

- $\frac { 1 } { - 200 }$ = $\frac { 1 } { + 30 }$ Ž v₀ = 35.3 cm

L = v₀ + f_e = 35.3 + 3 = 38.3 cm