Question

Bottom of glass beaker is made of a thin equiconvex lens having bottom side silvered polished as shown in figure. Now the water is filled in the beaker upto a height of h = 4m. The image of point object floating at middle point of beaker at the surface of water coincides with it. Find out the value of radius of curvature of lens $\left( { } _ { a } \mu _ { g } = \frac { 3 } { 2 } , { } _ { a } \mu _ { w } = \frac { 4 } { 3 } \right)$ -

• A. 3
• B. 5
• C. 8
• D. 10

Answer 1

Answer: (B)

5

Answer 2

if ray incident on lens or equivalent mirror incident normally then light retrace its path and final image will coincide with object

\ f of mirror should be = $\frac { 3 } { 2 }$ metre

\ =

$\frac { 2 } { 3 }$ =

$\frac { 2 } { 3 }$ =

R = 5 metre