## Practice Problem

Brynne Keyser 1B
Posts: 31
Joined: Fri Apr 06, 2018 11:03 am

### Practice Problem

If 3.607 x 10-19 J is required to remove an electron with zero kinetic energy from a metal surface, what would be the longest wavelength light that could do this?

From a previous chemistry community post, I know that you use the KE = energy of a photon + work function equation, but I am confused as to how to find the kinetic energy.

Alicia Yu 1A
Posts: 30
Joined: Thu Feb 22, 2018 3:02 am

### Re: Practice Problem

Because there is zero kinetic energy given in the question, we know that the equation to use would be KE = Ep - energy needed to eject an electron (threshold). The threshold is given as 3.607 x 10-19 J and KE would be zero.
Solving algebraically for wavelength by setting Ep = $\frac{hc}{\lambda }$