Question

Two converging lenses of the same focal length f are separated by distance 2f. The axis of the second lens is inclined at angle q = 60ŗ with respect to the axis of the first lens. A parallel para axial beam of light is incident from left side of the lens, then –

• A. Final image after all possible refraction will formed at optical centre of first lens
• B. Final image after all possible refraction will formed at optical centre of second lens
• C. Final image after all possible refraction will formed at distance f from second lens
• D. Final image after all possible refraction will formed at distance of f from first lens

Answer 1

Answer: (A)

Final image after all possible refraction will formed at optical centre of first lens

Answer 2

u = – f cos 60⁰

f = +f

= $\frac { 1 } { \mathrm { v } }$ –

= +

$\frac { 1 } { \mathrm { f } }$ – =

v = – f

= cos 60⁰

= x

x = 2f

\ final image will formed at optical centre of first lens.