JEE Main · 2026 · 06 Apr 2026 · Shift 1 · Geometrical Optics

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A spherical interface lens of radius R separates two media of refractive indices 1 and 1.4 respectively as shown in the figure below. A point source is placed at a distance of 4 R in front of spherical interface. The magnitude of the magnification of point source image is

____

(A)1.66✓ Correct
(B)2.33
(C)2.66
(D)1.33

Answer: (A)

Solution

Refraction at the single spherical surface obeys

\frac{n _{2}}{v} - \frac{n _{1}}{u} = \frac{n _{2} - n _{1}}{R}

. With

n_{1} = 1

n_{2} = 1.4

u = - 4 R

and the surface convex toward the source (

R > 0

\frac{1.4}{v} + \frac{1}{4 R} = \frac{0.4}{R}

, so

\frac{1.4}{v} = \frac{0.15}{R}

and

v = \frac{28 R}{3}

. The magnification is

m = \frac{n _{1} v}{n _{2} u} = \frac{1 \times 28 R /3}{1.4 \times ( - 4 R )} = - 1.67

. Its magnitude is about

1.66

JEE Main · 2026 · 06 Apr 2026 · Shift 1 · Single correct option

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JEE Main · 2026 · 06 Apr 2026 · Shift 1 · Geometrical Optics

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