# Ejecting Electrons with Light

The minimum frequency of light needed to eject electrons from a metal is called the threshold.

Find the minimum energy needed to eject electrons from a metal with a threshold frequency of 3.27*10^14s^-1.

With what kinetic energy will electrons be ejected when this metal is exposed to light with a wavelength of lamda = 245 nm?

KE_electron = _________ J

HINT:

Energy is related to frequency via E = hv.

The energy of the ejected electron is the difference between the minimum required energy and the energy of the light. You're given the wavelength of the light (lambda = 245 nm) which you'll need to convert to energy using E = hc/lambda.

Recall that h is Planck's constant (h = 6.626*10^-34 J*s) and c is the speed of light (c=2.998*10^8 m/s).

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#### Solution Preview

1. Solving for the minimum energy needed to eject the electron:

E = h?

E = (6.626 Ã— 10-34 JÂ·s)(3.27 x 1014/s)

E = 2.17 x 10-19 J

2. To solve for the ...

#### Solution Summary

This solution provides calculations for various questions involving ejecting electrons with light.