Longest wavelength of visible light:

**The reasoning** Think of visible light as a rainbow — from violet through blue, green, yellow, orange, to red. Wavelength is the distance between wave peaks. The electromagnetic spectrum follows this pattern: **the more energy a color has, the shorter its wavelength**. Violet light vibrates fastest (highest frequency, most energy) so it has the *shortest* wavelength (~400 nm). Red light vibrates slowest (lowest frequency, least energy) so it has the *longest* wavelength (~700 nm). **Why the wrong options tempt you** - **Violet** — It's at one extreme of the spectrum, so students confuse "first" with "longest." But violet is actually the *shortest*. - **Green/Yellow** — These sit in the middle, so they seem like safe guesses. They're neither extreme. The trap is thinking position in the rainbow means length. It doesn't — it means energy level. **Quick takeaway** **"ROY G. BIV goes from long to short"** — Red has the longest wavelength, Violet the shortest. Remember: red light relaxes (low energy, long waves), violet vibrates vigorously (high energy, short waves).