Problem — Frequency of yellow light

Problem

Yellow light has wavelength $\lambda = 600\;\text{nm}$ in vacuum. Calculate its frequency (use $c = 3{,}0\cdot 10^8\;\text{m/s}$).

Solution

Setting up. For every wave $c = \lambda f$, so $f = c/\lambda$. First convert the wavelength to metres: $600\;\text{nm} = 600\cdot 10^{-9}\;\text{m} = 6{,}0\cdot 10^{-7}\;\text{m}$.

Calculation.

$f = \frac{c}{\lambda} = \frac{3{,}0\cdot 10^8}{6{,}0\cdot 10^{-7}} \approx 5{,}0\cdot 10^{14}\;\text{Hz}$

$\ev{f \approx 5{,}0\cdot 10^{14}\;\text{Hz}}$

About $500$ terahertz, a typical value for visible light.

Connections

Topics: Electromagnetic waves Skills: Unit conversion