JEE Physics 2026 Question with Solution

Given: The lens is formed by combining two plano-convex parts with refractive indices $\mu_1 = 1.5$ and $\mu_2 = 1.2$. Their radii are $R_1 = 15 \, \text{cm}$ and $R_2 = 12 \, \text{cm}$. The object is placed at $u = -30 \, \text{cm}$.

Find: The magnification of the image.

Using the thin lens combination idea given in the solution:

So,

Hence,

Now apply the lens formula used in the solution:

Substituting $u = -30 \, \text{cm}$ and $f = 20 \, \text{cm}$,

Therefore,

The magnification is

the solution then states: Considering sign convention and thickness correction,

This matches option A. There is a discrepancy because the direct thin-lens calculation gives $-2$, but the provided solution concludes $-2.5$ and identifies A as correct.

Therefore, according to the provided the solution, the correct option is A, and the magnification is $-2.5$.

Given: the solution computes the equivalent focal length as $20 \, \text{cm}$ and then uses the lens formula with object distance $30 \, \text{cm}$.

Find: Whether the final marked option is consistent with the shown working.

From the shown working,

Then,

so

and hence

Thus the displayed algebra supports option D numerically. However, the source solution explicitly declares option A and adds a statement about thickness correction to reach $-2.5$. Following the instruction that the solution is the primary source, the recorded answer is A.