### Correct Option: A. Blue and Red #### Detailed Explanation: To understand why the correct answer is A (Blue and Red), we need to delve into the nature of light and how it is separated into its constituent colors, particularly when white light passes through a prism. 1. **Understanding White Light**: - White light is made up of a spectrum of colors, which can be seen when light is dispersed. The visible spectrum includes red, orange, yellow, green, blue, indigo, and violet (often abbreviated as ROYGBIV). 2. **Dispersion of Light**: - When white light passes through a prism, it bends (refracts) at different angles depending on the wavelength of the light. Shorter wavelengths (like blue and violet) bend more than longer wavelengths (like red and orange). This phenomenon is known as dispersion. 3. **Wavelengths of Colors**: - The wavelengths of the colors in the visible spectrum vary: - Red: ~620-750 nm - Orange: ~590-620 nm - Yellow: ~570-590 nm - Green: ~495-570 nm - Blue: ~450-495 nm - Indigo: ~425-450 nm - Violet: ~380-425 nm - From this, we can see that blue light has a shorter wavelength than red light. 4. **Separation in the Spectrum**: - The separation between colors in the spectrum is determined by the difference in their wavelengths. Blue (around 450 nm) and red (around 700 nm) are at opposite ends of the visible spectrum, which means they are separated by a significant distance when light is dispersed. - In contrast, the other pairs of colors listed in the options are closer together in terms of their wavelengths, leading to less separation. #### Analysis of Other Options: - **B. Green and Yellow**: - Green (495-570 nm) and yellow (570-590 nm) are relatively close in wavelength. The difference between them is only about 20 nm, which is much smaller than the difference between blue and red. - **C. Indigo and Violet**: - Indigo (425-450 nm) and violet (380-425 nm) are also close together, with a difference of about 25 nm. This is still significantly less than the separation between blue and red. - **D. Orange and Red**: - Orange (590-620 nm) and red (620-750 nm) are closer than blue and red, with a difference of about 30 nm. Again, this is much smaller than the separation between blue and red. ### Summary of Key Points: - **Wavelengths**: Blue light has a shorter wavelength (~450 nm) compared to red light (~700 nm), leading to greater separation. - **Dispersion**: The bending of light in a prism causes different colors to spread out based on their wavelengths. - **Color Pairs**: The pairs of colors in options B, C, and D are closer together in the spectrum, resulting in less separation than the blue and red pair. ### Revision Summary: - White light consists of a spectrum of colors that can be separated by a prism. - Blue and red light are at opposite ends of the visible spectrum, leading to the widest separation. - Dispersion causes different wavelengths to bend at different angles, affecting their separation. - Other color pairs (green/yellow, indigo/violet, orange/red) are closer together, resulting in less separation.