Science — CBSE Class 10 board question

Dispersion of White Light:
The splitting of white light into its seven constituent colours (VIBGYOR) on passing through a prism is called dispersion.

Cause:
Different colours of light have different speeds in glass, so they bend through different angles on refraction. Violet bends the most and red bends the least, causing them to separate.

Diagram:

```
White light
|
___________\___________
| \ Glass Prism |
| \ |
|_______\______________|
\
\——— Violet
\—— Indigo
\— Blue
\- Green

• Yellow

Orange
Red
(Screen — VIBGYOR)
```

Source: Chapter 10, Section 10.4 — Dispersion of White Light by a Glass Prism

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• Definition (1 mark): State that splitting of white light into VIBGYOR is called dispersion.
• Cause (1 mark): Different colours travel at different speeds in glass → different degrees of bending. Violet bends most, red bends least.
• Diagram (1 mark): Draw a triangular prism with a single white ray entering one face and seven colours (VIBGYOR order) emerging from the other face, fanning out onto a screen. Label "White light," the prism, and at least "Violet" and "Red" at the two ends of the spectrum.