When a beam of white light passes through a glass prism, it splits into its constituent colours. This phenomenon is called dispersion of light through a prism.
A prism is a transparent optical medium having two refracting surfaces inclined at an angle to each other.
Different colours of light have different wavelengths and hence different refractive indices in glass. As a result, they deviate by different angles.
The order of colours in the spectrum obtained through a prism is:
VIBGYOR
The angle between the incident ray and the emergent ray is called the angle of deviation.
Q1. Dispersion of white light through prism occurs due to: A) Reflection B) Equal speed of colours C) Different refractive indices for different colours D) Absorption of light Answer: C Q2. Which colour deviates the most in a prism? A) Red B) Yellow C) Green D) Violet Answer: D Q3. Which colour deviates the least in a prism? A) Violet B) Blue C) Green D) Red Answer: D Q4. The order of colours obtained in spectrum is: A) RYGBIVO B) VIBGYOR C) RGBVIOY D) YORGBIV Answer: B Q5. Dispersion shows that white light is: A) Pure light B) Monochromatic C) Polychromatic D) Invisible Answer: C Q6. Angle of deviation depends on: A) Colour of light B) Refractive index C) Angle of incidence D) All of the above Answer: D Q7. In a prism, different colours emerge because they: A) Travel in straight line B) Have same wavelength C) Have different speeds D) Have same deviation Answer: C Q8. Which statement is correct? A) Red has highest refractive index B) Violet has lowest refractive index C) Violet deviates more than red D) All colours deviate equally Answer: C
Transparent medium with two inclined refracting surfaces.
Splitting of white light into colours due to different refractive indices.
VIBGYOR
Different speeds and refractive indices for different colours.
MCQs are frequently asked on order of colours, maximum/minimum deviation and cause of dispersion.
