**Problem:**

The red light from a helium-neon laser has a frequency of 4.74 x 10

^{14}Hz. What is the energy of one photon?

**Solution:**

E = hν where

E = energy

h = Planck's constant = 6.626 x 10

^{-34}J·s

ν = frequency

E = hν

E = 6.626 x 10

^{-34}J·s x 4.74 x 10

^{14}Hz

E = 3.14 x

^{-19}J

**Answer:**

The energy of a single photon of red light from a helium-neon laser is 3.14 x

^{-19}J.