IIT JEE Physics Practice Paper – Optics (Set 4)

Instructions

Total Questions: 30 | Marks: 4 each | No Negative Marking

Q1. Refractive index is defined as:

c/v
v/c
λ/v
f/v

Q2. Snell’s law is:

n₁sinθ₁ = n₂sinθ₂
θ₁ = θ₂
n₁ = n₂
None

Q3. Critical angle occurs when:

Refraction angle = 90°
Incident angle = 90°
Both equal
None

Q4. Mirror formula is:

1/f = 1/v + 1/u
v = u + f
f = v/u
None

Q5. Power of lens is:

1/f
f
v/u
None

Q6. Unit of power of lens:

Diopter
Watt
Joule
Newton

Q7. Total internal reflection occurs when:

Denser to rarer medium
Rarer to denser
Same medium
None

Q8. Image formed by plane mirror is:

Virtual and erect
Real
Inverted
None

Q9. Magnification of mirror is:

-v/u
v/u
u/v
None

Q10. Dispersion of light is due to:

Different refractive indices
Same speed
Reflection
Absorption

Q11. Speed of light is maximum in:

Vacuum
Water
Glass
Air

Q12. Concave mirror focal length sign:

Negative
Positive
Zero
Infinite

Q13. Convex mirror forms image:

Virtual
Real
Both
None

Q14. Lens formula is:

1/f = 1/v – 1/u
1/f = 1/v + 1/u
v = u + f
None

Q15. Optical fiber works on:

Total internal reflection
Reflection
Refraction
Diffraction

Q16. Young’s double slit experiment proves:

Wave nature of light
Particle nature
Energy conservation
None

Q17. Fringe width depends on:

Wavelength
Mass
Charge
None

Q18. Diffraction occurs when:

Aperture size comparable to wavelength
Very large aperture
No aperture
None

Q19. Polarization proves:

Transverse nature of light
Longitudinal nature
Particle nature
None

Q20. Coherent sources have:

Same frequency
Different frequency
Random phase
None

Q21. Brewster angle relates to:

Polarization
Diffraction
Reflection
None

Q22. Optical path =

n × distance
distance
1/n
None

Q23. Convex lens produces real image when:

Object beyond F
At F
Inside F
None

Q24. Interference maxima condition:

Path difference = nλ
(n+½)λ
λ/2
None

Q25. Diffraction pattern central maxima is:

Brightest
Dark
Same
None

Q26. Wavefront is:

Surface of constant phase
Constant velocity
Constant energy
None

Q27. Huygens principle explains:

Wave propagation
Particle motion
Energy loss
None

Q28. Angular magnification depends on:

Focal length
Mass
Charge
None

Q29. Telescope works on:

Refraction
Diffraction
Polarization
None

Q30. Microscope magnification depends on:

Focal length
Velocity
Charge
None

Submit

Optics – IIT JEE Notes (Set 4)

Refractive Index

Definition

Refractive index (n) is defined as the ratio of speed of light in vacuum to speed of light in a medium.

Formula: n = c / v

Key Insight

Higher refractive index means light travels slower in that medium.

Refraction and Snell’s Law

Law

n₁ sinθ₁ = n₂ sinθ₂

Important Points

Light bends towards normal when entering denser medium and away from normal when entering rarer medium.

Total Internal Reflection (TIR)

Conditions

1. Light must travel from denser to rarer medium

2. Angle of incidence must be greater than critical angle

Applications

Optical fibers, diamond sparkle, mirage formation

Mirror Formula and Magnification

Formula

1/f = 1/v + 1/u

Magnification

m = -v/u

Key Insight

Negative magnification indicates inverted image.

Lens Formula and Power

Lens Formula

1/f = 1/v – 1/u

Power of Lens

P = 1/f (in meter)

Unit

Diopter (D)

Image Formation by Lenses

Convex Lens

Forms real image when object is beyond focal point and virtual image when inside focal length.

Concave Lens

Always forms virtual, erect, and diminished image.

Dispersion of Light

Concept

White light splits into colors due to different refractive indices for different wavelengths.

Key Insight

Violet deviates most, red deviates least.

Interference of Light

Condition

Constructive interference: path difference = nλ

Destructive interference: path difference = (2n+1)λ/2

Young’s Double Slit Experiment

Demonstrates wave nature of light.

Diffraction

Concept

Bending of light around edges or through small apertures.

Key Insight

Occurs when aperture size is comparable to wavelength.

Polarization

Concept

Polarization proves that light is a transverse wave.

Brewster’s Law

tanθ = n

Wavefront and Huygens Principle

Wavefront

A surface of constant phase.

Huygens Principle

Every point on a wavefront acts as a source of secondary wavelets.

Optical Instruments

Microscope

Magnification depends on focal length of objective and eyepiece.

Telescope

Used for viewing distant objects, works on refraction or reflection.

Important Exam Concepts

Conceptual Traps

Light speed changes but frequency remains constant during refraction. Magnetic field does not affect light path.

JEE Strategy

Focus on sign conventions, formulas, and diagram-based understanding. Practice numerical problems regularly.