PREPWISER.
Practise online

Ray Optics revision notes

Every idea in the Ray Optics chapter for JEE Main, with the usual mistakes and the fast methods. Topic 1 is open to everyone; sign in free to read all 33 and download the PDF.

Sign in to read all 33Download PDF

Read the first part free. Sign in free with Google to read the rest and download the PDF: 13 A4 pages.13 A4 pages, ready to print.

How we count: 7× asked means 7 past JEE Main questions in the PrepWiser bank needed that concept, and "last" is the latest year one appeared. ★ marks ideas asked 8 or more times.

Reflection and plane mirrors

Laws of reflection
2× asked, last 2023
b^=a^−2(a^⋅n^) n^,δ=180∘−2i\hat b = \hat a - 2(\hat a\cdot\hat n)\,\hat n,\qquad \delta = 180^\circ - 2i
a^\hat a, b^\hat b: incident, reflected unit vectors; n^\hat n: unit normal. Mirror turned by θ\theta turns the ray 2θ2\theta.
Plane mirror image
3× asked, last 2023
vimage=2vmirror−vobject,Lmin⁡=H2v_{\text{image}} = 2v_{\text{mirror}} - v_{\text{object}},\qquad L_{\min}=\frac{H}{2}
Velocities along the normal. Image: virtual, erect, same size, laterally inverted, as far behind. Lmin⁡L_{\min}: full height HH.
  • Not dd. When the mirror moves dd towards a fixed object, the image moves 2d2d the same way: the mirror shifts dd and the image–mirror gap shrinks by dd.
Two inclined mirrors
3× asked, last 2023
n=360∘θ−1,δtwo reflections=360∘−2θn = \frac{360^\circ}{\theta}-1,\qquad \delta_{\text{two reflections}} = 360^\circ - 2\theta
m=360∘/θm=360^\circ/\theta. mm even: m−1m-1 images. mm odd: m−1m-1 on the bisector, mm off it. Parallel mirrors: infinitely many.
OI1I_1I2I_2I3I_390∘90^\circ
θ=90∘\theta=90^\circ: m=4m=4 (even), so 3 images

Practise Ray Optics questions as you read. Free, and you can start without signing up.

Practise Ray Optics

30 more concepts in 6 topics

Spherical mirrors, Refraction and total internal reflection, Spherical surfaces and thin lenses, Lens combinations and multi-element systems, Prism and dispersion and Optical instruments and the eye. Read the first part free. Sign in free with Google to read the rest and download the PDF.

Sign in to read the restYou come straight back to this spot.Download the PDF

Spherical mirrors

  • Mirror formula15×
  • Mirror magnification10×
  • Image nature (real object)5×
  • Along the axis: size and image speed6×

Refraction and total internal reflection

  • Snell's law12×
  • Speed, wavelength and frequency7×
  • Apparent depth and normal shift10×
  • Lateral shift in a glass slab4×
  • Critical angle and TIR14×
  • Source under water2×
  • Optical fibre and entry angle2×

Spherical surfaces and thin lenses

  • Refraction at a spherical surface14×
  • Thin lens formula10×
  • u–v graphs6×
  • Lensmaker's formula12×
  • Lens in a medium10×
  • Cutting or covering a lens6×
  • Displacement method1×

Lens combinations and multi-element systems

  • Power and lenses in contact11×
  • Lenses separated by d4×
  • Two-step imaging14×
  • Silvered lens4×

Prism and dispersion

  • Refraction through a prism8×
  • Minimum deviation18×
  • Thin prism7×
  • Dispersion5×
  • Prism combinations5×

Optical instruments and the eye

  • Simple microscope2×
  • Compound microscope7×
  • Astronomical telescope4×

Practise Ray Optics next

About 200 past JEE Main questions from this chapter, with instant answer checking and step-by-step solutions where available. Free, and you can start without signing up.

Practise Ray Optics

Also free on PrepWiser

Spotted a mistake? Write to support@prepwiser.in and we will fix it in the next version.

Version 1, October 2026. Free to share for study, as it is. Please don't sell it or remove the PrepWiser name.

PractiseSign in to read all 33Download PDF
Free with Google, takes a few seconds13 pages, free