Question

An equiconvex lens of radius of curvature 14 cm is made up of two different materials. Left half and right half of vertical portion is made up of material of refractive index 1.5 and 1.2 respectively as shown in the figure. If a point object is placed at a distance of 40 cm, calculate the image distance.

• A. 25 cm
• B. 50 cm
• C. 35 cm
• D. 40 cm

Answer 1

The Correct Option is C

For lenses with different materials, we need to use the lens maker’s formula:
\( \frac{1}{f} = (n_1 - 1)\left(\frac{1}{R_1} - \frac{1}{R_2}\right) \)
where \( n_1 \) and \( n_2 \) are the refractive indices of the two materials, and 
\( R_1 \) and \( R_2 \) are the radii of curvature of the lens surfaces. 

After applying the appropriate values for the refractive indices and the radii of curvature, we find the image distance to be 35 cm.