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

Question

The minimum frequency of light needed to eject electrons from a metal is called the threshold frequency. Find the minimum energy needed to eject electrons from a metal with a threshold frequency of 5.05 x 10^14.

I got that answer it is: 3.35 x 10^-19J

With what kinetic energy will electrons be ejected when this metal is exposed to light with a wavelength of 255nm?

KEelectron = ________________ J

(I attempted an answer and it was wrong. I received a note to use E=hc/wavelength, then subtract the answer from above of 3.35 x 10^-19. I have done that and still not been able to get the correct answer)

Please explain your answer, I need to understand why I am not getting this!! thanks

Explanation / Answer

Minimum energy= h*vthreshold

=6.62*10-34*5.05*1014

=3.346*10-19 J or 3.35*10-19J

Energy of light to which metal is exposed=hc/?

=6.22*10-34*3*108/255*10-9

=7.795*10-19 J

KE of electron=(7.795-3.346)*10-19 J

=4.449*10-19=4.45*10-19 J

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