Question

A double convex lens made of glass of refractive index 1.56 has both radii of curvature of magnitude 20 cm. If an object is placed at a distance of 10 cm from this lens. The position of the image formed is:

• A. 22.86 same side of the object
• B. 22.86 opposite side of the object
• C. 44.89 same side of the object
• D. 44.89 opposite side of the object

Answer 1

Answer: (A)

22.86 same side of the object

Answer 2

: Using $\frac { 1 } { \mathrm { f } } = ( \mu - 1 ) \left( \frac { 1 } { \mathrm { R } _ { 1 } } - \frac { 1 } { \mathrm { R } _ { 2 } } \right)$

Here,$\mu = 1.56$

$\frac { 1 } { \mathrm { f } } = ( 1.56 - 1 ) \left( \frac { 1 } { 20 } + \frac { 1 } { 20 } \right)$

Now, from lens equation,

Since v is negative, the image will be formed on the same side as that of object.