The work function for a particular metal is 4.0 eV.Which one of the following best describes the wavelength of electromagnetic radiation needed to eject electrons from this metal?
A)310 nm or greater
B)310 nm or smaller
C)620 nm or greater
D)620 nm or smaller
E)800 nm or greater

Question

Quizplus · Accepted Answer

The work function is the minimum energy needed to eject an electron from the metal. To find the wavelength corresponding to this energy, we use the equation $E = \frac{hc}{\lambda}$, where $E$ is the energy in electron volts (eV), $h$ is Planck's constant ($4.135667696 \times 10^{-15}$ eV·s), $c$ is the speed of light ($3 \times 10^8$ m/s), and $\lambda$ is the wavelength in meters. Solving for $\lambda$ gives a value smaller than 310 nm, meaning electromagnetic radiation with a wavelength smaller than 310 nm is needed to provide the energy of 4.0 eV or greater to eject electrons.

The Work Function for a Particular Metal Is 4