Practice!

Sample Problem

What is the kinetic energy of an electron with a frequency of 8.3 × 1014Hz? Estimate h as 4.14 × 10-15 eVs.

Solution

We use the equation E = hf. We plug in the values we are given and get

E = (4.14 × 10-15) (8.3 × 1014) = 3.4eV.