While analyzing the dispersion of white light through a glass prism, a student wonders why the colors appear in a specific order from top to bottom on the screen. What is the main reason for this observed sequence?
Different wavelengths of light bend at different angles due to varying refractive indices
White light is a mixture of seven colours, each with a different wavelength, from red (longest) to violet (shortest). When it passes through a glass prism, it splits into these colours; this splitting is called dispersion.
The refractive index of glass is different for different wavelengths: it is the largest for violet and the smallest for red. So violet light is bent (deviated) the most and red light the least, and each colour leaves the prism at its own angle.
This is why the colours always appear in the fixed order VIBGYOR on the screen, with red at the top, nearest the original direction, and violet at the bottom.
The colours do not arrange themselves; the order comes from refraction. The prism lets all colours pass through, and if every colour were deviated by the same angle, they would stay together and no spectrum would form.
Hence, Different wavelengths of light bend at different angles due to varying refractive indices.
Similar Questions
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(iv) Refraction makes a white wall appear colored at night.
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Important Questions from Optics
Who was the first one to use a glass prism to obtain the spectrum of sunlight?
Twinkling of stars is due to:
In which a convex mirror is used?
A. Rear View mirrors in vehicles
B. Glass windows
C. Makeup Mirror
D. Kaleidoscope
An object is placed 10 cm in front of a lens. The image formed is real, inverted and of same size as the object. What is the focal length and nature of the lens?
The power of a lens is -2.5 D. The type of lens and its focal length are respectively:
