Ray Optics · JEE Main previous year questions

2026 33 questions

1. Q402026 · 23 Jan 2026 · Shift 2

   A prism of angle $75^{\circ }$ and refractive index $\sqrt{3}$ is coated with thin film of refractive index 1.5 only at the back exit surface. To have total internal reflection at the back exit surface the incident angle must be _____ $(\sin 15^{\circ }=0.25\text{ and }\sin 25^{\circ }=0.43)$

   1. A.between $15^{\circ }$ and $20^{\circ }$
   2. B.$15^{\circ }$
   3. C.$<15^{\circ }$
   4. D.$>25^{\circ }$
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   Answer: A, B, C

2. Q462026 · 23 Jan 2026 · Shift 2· Numerical answer

   The size of the images of an object, formed by a thin lens are equal when the object is placed at two different positions 8 cm and 24 cm from the lens. The focal length of the lens is _____ cm.

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   Answer: 16

3. Q262026 · 22 Jan 2026 · Shift 1

   A thin convex lens of focal length 5 cm and a thin concave lens of focal length 4 cm are combined together (without any gap) and this combination has magnification $m_1$ when an object is placed 10 cm before the convex lens. Keeping the positions of convex lens and object undisturbed a gap of 1 cm is introduced between the lenses by moving the concave lens away, which lead to a change in magnification of total lens system to $m_2$. The value of $\left|\frac{m_1}{m_2}\right|$ is ____.

   1. A.$\frac{25}{27}$
   2. B.$\frac{5}{6}$
   3. C.$\frac{5}{27}$
   4. D.$\frac{3}{2}$
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   Answer: B

4. Q272026 · 22 Jan 2026 · Shift 1

   Consider an equilateral prism (refractive index $\sqrt{2}$). A ray of light is incident on its one surface at a certain angle $i$. If the emergent ray is found to graze along the other surface then the angle of refraction at the incident surface is close to ____

   1. A.$30^{\circ }$
   2. B.$20^{\circ }$
   3. C.$40^{\circ }$
   4. D.$15^{\circ }$
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   Answer: D

5. Q492026 · 22 Jan 2026 · Shift 1· Numerical answer

   A parallel beam of light travelling in air (refractive index 1.0) is incident on a convex spherical glass surface of radius of curvature 50 cm . Refractive index of glass is 1.5 . The rays converge to a point at a distance $x\mathrm{cm}$ from the centre of the curvature of the spherical surface. The value of $x$ is ____ cm .

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   Answer: 100

6. Q472026 · 21 Jan 2026 · Shift 1· Numerical answer

   In a microscope the objective is having focal length $f_o=2\mathrm{cm}$ and eye-piece is having focal length $f_e=4\mathrm{cm}$. The tube length is 32 cm . The magnification produced by this microscope for normal adjustment is ____.

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   Answer: 100

7. Q492026 · 21 Jan 2026 · Shift 1· Numerical answer

   A collimated beam of light of diameter 2 mm is propagating along $x$-axis. The beam is required to be expanded in a collimated beam of diameter 14 mm using a system of two convex lenses. If first lens has focal length 40 mm , then the focal length of second lens is ____ mm.

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   Answer: 280

8. Q382026 · 21 Jan 2026 · Shift 2
   
   1. A.$75^{\circ }$
   2. B.$90^{\circ }$
   3. C.$60^{\circ }$
   4. D.$45^{\circ }$
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   Answer: C