Question

State the correct sequence (1-7) of colors in the spectrum formed by the prisms A and B, shown in Figure 15.2

Answer 1

Dispersion:

1. The splitting of white light into its constituent colors is called dispersion.
2. This phenomenon can be noticed when white light is passed through a triangular prism.
3. In general, white light disperses into 7 colors, namely, violet, indigo, blue, green, yellow, orange, and red (VIBGYOR).

Solution:

1. In the figure, white light is passed through a prism and hence it will be split into 7 colors.
2. When a white light disperses into its 7 constituent colors the order of different colors of the spectrum is fixed as per the wavelength of the different colors.
3. The color Red has the highest wavelength so its travels less and hence bends less.
4. The violet has the least wavelength so it travels more and hence it bends more than other colors.
5. The band of colors can be understood from the following figure:

Hence, due to the dispersion of light, a band of colors is seen when white light is passed through a prism.