You Want to Have an Electron in an Energy Level

Multiple Choice

You want to have an electron in an energy level where its speed is no more than 66 m/s.What is the length of the smallest box (an infinite well) in which you can do this? (h = 6.626 × 10^-34 J ∙ s,m_el = 9.11 × 10^-31 kg)

A) 5.5 µm
B) 11 µm
C) 2.8 µm
D) 1.4 µm