Question

A double convex lens made of material of refractive index m₁ is placed inside two liquids of refractive index µ₂ and µ₃ as shown in figure where m₂>m₁>m₃. A wide parallel beam of light is incident on lens from left. The lens will give rise to –

• A. Single convergent beam
• B. Two different convergent beam
• C. Two different divergent beam
• D. A convergent and divergent beams

Answer 1

Answer: (D)

A convergent and divergent beams

Answer 2

=

(focal length of upper part of lens)

$\frac { 1 } { \mathrm { f } _ { 2 } }$ = $\frac { \mu _ { 3 } - \mu _ { 1 } } { \mu _ { 1 } }$ $\left[ \frac { 2 } { \mathrm { R } } \right]$

(focal length of lower part of lens)

as m₂ > m₁ f₁ = +ve converging lens

as m₃ < m₁ f₂ = –ve diverging lens