Physics

Class 10

Interactive Science Lab

Dispersion of Light (VIBGYOR Prism)

Explore the splitting of white light into 7 constituent colors through a glass prism and raindrop rainbow formation.

Dispersion of Light Simulator

Explore how a triangular glass prism refracts and separates composite white light into its seven constituent colors (VIBGYOR) due to wavelength-dependent refractive indices.

Class 10 Physics

Unit 12: Section 12.1

Glass Prism Dispersion

Angle of Incidence: 48°

Crown Glass (Standard)

Spectrum: VIBGYOR (7 Colors)

Optics & Simulation Parameters

Simulation Concept Mode

Angle of Incidence (i)

48°

Angle between the incident white beam and the normal to the first prism surface.

30° (Steep)48° (Standard)70° (Glancing)

Prism Optical Material

n ≈ 1.52

Higher refractive index materials bend light more and exhibit greater color dispersion.

Standard Board Experiment Scenarios

Optics & Simulation Parameters

Simulation Concept Mode

Angle of Incidence (i)

48°

Angle between the incident white beam and the normal to the first prism surface.

30° (Steep)48° (Standard)70° (Glancing)

Prism Optical Material

n ≈ 1.52

Higher refractive index materials bend light more and exhibit greater color dispersion.

Standard Board Experiment Scenarios

Live Optical Measurements & Deviation

Computed using Snell's Law at both prism surfaces for each individual wavelength.

Unit 12: Dispersion of Light

Incident Angle (i)

48°

Prism A = 60°

Medium Index (n)

1.52

Crown

Red (λ=700nm)

δ = 38.33°

n = 1.513 (Bends Least)

Violet (λ=400nm)

δ = 41.27°

n = 1.545 (Bends Most)

Angular Spread

Δθ = 2.94°

δ_Violet − δ_Red

Dispersive Power (ω)

0.0615

(n_V − n_R) / (n_Y − 1)

Fundamental Law of Optical Dispersion

In a glass prism, shorter wavelengths of light travel slower than longer wavelengths (v = c / n). Because Violet light (400 nm) encounters the highest refractive index (n = 1.545), it bends by the greatest angle (δ = 41.27°). Conversely, Red light (700 nm) encounters the lowest index (n = 1.513) and bends the least (δ = 38.33°).

Step-by-Step Physics Derivations & Calculations

Class 10 Physics — Unit 12: Electromagnetic Spectrum & Dispersion (Sindh & Karachi Boards)

Step 1[degrees]

Snell's Law at 1st Prism Surface

n₁ sin(θ₁) = n₂ sin(r₁)

Sub: 1.00 × sin(48°) = 1.52 × sin(r₁)

Result:r₁ = 29.27° (Yellow mean)

White light enters from air into glass and bends toward the normal line.

Step 2[degrees]

Internal Prism Geometry

r₁ + r₂ = A

Sub: 29.27° + r₂ = 60°

Result:r₂ = 30.73°

Angle of incidence at second surface inside the prism.

Step 3[degrees]

Snell's Law at 2nd Prism Surface

n₂ sin(r₂) = 1.00 sin(e)

Sub: 1.52 × sin(30.73°) = 1.00 × sin(e)

Result:e = 50.96°

Light emerges into air and bends away from the normal, fanning out further.

Step 4[degrees]

Total Angle of Deviation (δ)

δ = i + e - A

Sub: δ = 48° + 50.96° - 60°

Result:δ_Red = 38.33°, δ_Violet = 41.27°

Violet bends most (41.27°) because it has the highest refractive index (1.545).

Step 5

Angular Spread & Dispersive Power

Δθ = δ_V - δ_R | ω = (n_V - n_R) / (n_Y - 1)

Sub: Δθ = 41.27° - 38.33° = 2.94°

Result:Angular Spread = 2.94°, ω = 0.0615

Crown Glass (Standard) separates colors over an angular width of 2.94°.

Complete VIBGYOR Spectrum Breakdown (Class 10 Textbook Table)

Color	Wavelength (λ)	Frequency (f)	Refractive Index (n)	Speed in Glass	Angle of Deviation (δ)	Bending Amount
Red	620–750 nm	~441.2 THz	1.513	1.983 × 10⁸ m/s	38.33°	Minimum (Least)
Orange	590–620 nm	~495.9 THz	1.517	1.978 × 10⁸ m/s	38.69°	Moderate
Yellow	570–590 nm	~517.2 THz	1.520	1.974 × 10⁸ m/s	38.96°	Moderate
Green	495–570 nm	~566 THz	1.526	1.966 × 10⁸ m/s	39.51°	Moderate
Blue	450–495 nm	~638.3 THz	1.532	1.958 × 10⁸ m/s	40.06°	Moderate
Indigo	420–450 nm	~689.7 THz	1.538	1.951 × 10⁸ m/s	40.61°	Moderate
Violet	380–420 nm	~750 THz	1.545	1.942 × 10⁸ m/s	41.27°	Maximum (Most)

Class 10 Board High-Yield Concepts & Definitions

Dispersion of Light: The splitting of composite white light into its constituent seven colors when passed through a prism or transparent refracting medium.
Spectrum: The continuous band of colored lights obtained on a screen when white light undergoes dispersion. The colors appear in the order: VIBGYOR (Violet, Indigo, Blue, Green, Yellow, Orange, Red).
Wave Equation in Medium: v = f × λ and n = c / v. The frequency (f) of light remains constant across media, but wavelength (λ) and speed (v) decrease inside glass.
Cause of Dispersion: Glass has different refractive indices for different wavelengths of light. Shorter wavelength (Violet) slows down most and refracts the most, while longer wavelength (Red) slows down least and refracts the least.

Real-World Applications & Natural Phenomena of Dispersion

1. Natural Rainbow Formation

Natural Atmospheric Optics

Millions of suspended raindrops act as tiny spherical prisms. Sunlight undergoes refraction upon entering, internal reflection at the curved back wall, and refraction upon exiting, casting an arc of colors from 40° (Violet) to 42° (Red).

2. Diamond Brilliance & Fire

Total Internal Reflection

Diamond has an exceptionally high refractive index (n ≈ 2.42) and a very small critical angle (24.4°). Light undergoes multiple total internal reflections before exiting, separating widely into vivid colored flashes known as 'fire'.

3. Astronomical Spectroscopy

Astrophysics & Chemistry

Astronomers pass starlight through optical prisms and spectrometers to disperse light into spectral lines. Dark absorption lines (Fraunhofer lines) reveal the exact chemical elements (Hydrogen, Helium, Iron) present in distant stars.

4. Chromatic Aberration in Lenses

Camera & Optical Design

Simple glass lenses focus different colors at slightly different focal points due to dispersion, producing purple/red color fringing around image edges. Optical engineers combine Crown and Flint glass (achromatic doublets) to correct this.

Class 10 Core Board Examination Takeaways

White light is polychromatic (composed of 7 constituent colors: VIBGYOR).
In a vacuum, all light colors travel at the same velocity (3 × 10⁸ m/s).
In glass, Violet light travels slowest, has the highest refractive index, and undergoes the maximum deviation.
In glass, Red light travels fastest, has the lowest refractive index, and undergoes the minimum deviation.

Board Exam Concept Checks

Class 10 Physics: Dispersion of Light & Refraction in Prisms

Question 1

Class 10 Physics — Unit 12 (Dispersion of Light)

Maximum Deviation in Prism

When white light passes through a glass prism, which color undergoes the MAXIMUM deviation (bends the most)?

Question 2

Class 10 Physics — Electromagnetic Waves

Speed of Light in Vacuum vs Glass

In a vacuum, Red light and Violet light travel at:

Question 3

Class 10 Physics — Natural Dispersion Phenomena

Rainbow Formation in Water Droplets

Which sequence of optical phenomena takes place inside a raindrop to form a primary rainbow?

Question 4

Class 10 Physics — Visible Light Spectrum

VIBGYOR Sequence Order

Arrange the visible spectrum colors in order of DECREASING wavelength (Longest to Shortest):

Syllabus Mapping & Learning Objectives

This interactive tool is modeled directly after the official Pakistani textbook curriculam (Sindh Textbook Board, Federal Board Islamabad, and Punjab Textbook Board). It provides live parameter tuning so students can test hypotheses, predict exam outcomes, and observe physical/chemical laws mathematically.

Key Topics Covered

LightRefractionPrismDispersionVIBGYORRainbow

More Study Resources

Pair this simulation with verified solved board past papers and chapter revision notes.

Solved Board Past Papers Chapter-Wise Revision Guides Online Scientific Calculator