Question

What is the frequency of yellow light with a wavelength of 580 nm? 1. 5.2 × 1014 hz 2. 1.9 × 10−17 hz 3. 5.2 × 1016 hz 4. 5.2 × 1012 hz 5. 1.9 × 10−15 hz?

Answer 1

Let's  convert the wavelength into meters first:
$\lambda=580 nm=580 \cdot 10^{-9}m$
Then we know that the frequency f is related to the wavelength by the following relationship:
$f= \frac{c}{\lambda}$
where $c=3\cdot 10^8 m/s$ is the speed of light. Substituting the numbers, we get the frequency:
$f= \frac{3\cdot 10^8 m/s}{580 \cdot 10^{-9}m}=5.2\cdot 10^{14}Hz$
So, this is approximately the frequency of yellow light.