1. What is Ray Optics?

Ray optics deals with light as rays, focusing on reflection, refraction, lenses, mirrors, and optical devices like microscopes and telescopes.

GenZ Example

The way your selfie looks in a mirror — that’s ray optics in action.

2. Important AAI ATC Focused Concepts

3. Laws of Reflection

Fundamental principles of reflection.

Angle of incidence = angle of reflection
Incident ray, reflected ray, and normal lie on same plane

PYQ Type: Theory MCQ

4. Refraction (Snell’s Law)

The law governing the bending of light as it passes between media.

\( n_1 \sin i = n_2 \sin r \)

PYQ Type: AAI ATC uses this for numerical or theory MCQ

5. Mirror Formula

The relationship between object distance, image distance, and focal length for mirrors.

\( \frac{1}{f} = \frac{1}{v} + \frac{1}{u} \)

Convex mirror: f is positive
Concave mirror: f is negative

Sign convention is very important

PYQ Asked: Mirror formula for concave mirror Q (2022)

6. Lens Formula

The relationship between object distance, image distance, and focal length for lenses.

\( \frac{1}{f} = \frac{1}{v} - \frac{1}{u} \)

Convex lens: f positive
Concave lens: f negative

7. Magnification

The ratio of image height to object height.

Mirror: \( m = \frac{h'}{h} = -\frac{v}{u} \)
Lens: \( m = \frac{h'}{h} = \frac{v}{u} \)

PYQ Type: Formula based

8. Power of Lens (in dioptre)

The reciprocal of focal length as a measure of lens strength.

\( P = \frac{100}{f \, (\text{in cm})} \) OR \( P = \frac{1}{f \, (\text{in m})} \)

Unit = D (Dioptre)
Convex lens: P > 0
Concave lens: P < 0

AAI ATC PYQ: Unit of lens power (2023)

9. Optical Instruments

Key formulas and concepts for optical devices.

Instrument	Formula / Concept
Simple Microscope	\( m = 1 + D/f \)
Compound Microscope	\( m = m_1 \times m_2 \)
Telescope (normal adjustment)	\( m = f_o / f_e \)
Angular magnification	Used in visual angle concept

PYQ Type: Optical instrument working theory MCQ

10. AAI ATC PYQ Analysis (2021–2023)

Year Question Asked

2021 Shift 2: Lens power unit (Dioptre), mirror formula

2022 Shift 3: Focal length sign MCQ, magnification formula

2023 Feb Shift 1: Optical instruments magnification, Snell’s Law

11. Ray Optics Formula Sheet (Quick Revision)

Concept	Formula
Mirror Formula	\( \frac{1}{f} = \frac{1}{v} + \frac{1}{u} \)
Lens Formula	\( \frac{1}{f} = \frac{1}{v} - \frac{1}{u} \)
Magnification (mirror)	\( m = -\frac{v}{u} \)
Magnification (lens)	\( m = \frac{v}{u} \)
Power of lens	\( P = \frac{100}{f_{\text{cm}}} = \frac{1}{f_{\text{m}}} \)
Snell’s Law	\( n_1 \sin i = n_2 \sin r \)
Microscope magnification	\( m = 1 + \frac{D}{f} \)
Telescope magnification	\( m = \frac{f_o}{f_e} \)

12. Quick Concept Recap (Gen Z Edition)

Concept	GenZ Example
Mirror image flipped	Selfie in front cam vs mirror view
Lens bending light	Glass of water bending straw’s look
Convex lens = converging	Magnifying glass in sun to burn paper
Concave lens = diverging	Peephole lens in hotel door
Power = strength of lens	Specs prescription: –2D, +1.5D etc.

13. Final AAI ATC Takeaway

Focus Areas:

Top 3 most asked Physics chapters
Mirror/lens formulas
Power of lens unit (D)
Focal length sign concept
Optical instrument magnification
Snell’s Law / basic refraction

14. 10-Question AAI ATC-Style MCQ Mock Test — Ray Optics

Q1. What is the unit of lens power?
a) Watt
b) Tesla
c) Dioptre
d) Lux
Ans: c

Q2. Convex lens has:
a) Negative power
b) Positive focal length
c) Negative focal length
d) None
Ans: b

Q3. Mirror formula is:
a) \( \frac{1}{f} = \frac{1}{v} + \frac{1}{u} \)
b) \( \frac{1}{f} = \frac{1}{u} - \frac{1}{v} \)
c) \( f = v + u \)
d) None
Ans: a

Q4. Lens formula is:
a) \( \frac{1}{f} = \frac{1}{v} - \frac{1}{u} \)
b) \( \frac{1}{f} = \frac{1}{v} + \frac{1}{u} \)
c) \( f = u + v \)
d) None
Ans: a

Q5. Power of a lens with focal length 50 cm is:
a) 2 D
b) 0.5 D
c) 20 D
d) 5 D
Ans: a

Q6. In concave mirror, focal length is:
a) Positive
b) Negative
c) Zero
d) Cannot be defined
Ans: b

Q7. Snell’s law is:
a) \( v = u + at \)
b) \( F = ma \)
c) \( n_1 \sin i = n_2 \sin r \)
d) \( q = mc\Delta T \)
Ans: c

Q8. Magnification of mirror is:
a) \( \frac{h}{h'} \)
b) \( -\frac{v}{u} \)
c) \( \frac{v}{u} \)
d) \( v \times u \)
Ans: b

Q9. For convex mirror, the image formed is:
a) Real, inverted
b) Virtual, erect
c) Enlarged
d) None
Ans: b

Q10. Which of the following is used to see distant objects?
a) Microscope
b) Periscope
c) Telescope
d) Projector
Ans: c