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istory Bookmarks Window Help saplinglearning.com Jump to... Print calculator bd Perodic Tube Question 12 of 29 Mapce Sapling Learning The minimum frequency of light needed to eject electrons from a metal is called the threshald frequency, vo Find the minimum energy needed to eject electrons from a metal with a threshold frequency of 529 x 10" Number With what maximun kinetic energy will electrons be ejected when this metal is exposed to light with a wavelength of 245 nm? Number Previous Give Up&iew; Soion Check Answer Next Ext about us careers prvacy polcyerms of use coneact us help 29

Explanation / Answer

Answer:

a) Given threshold frequency v0=5.29x1014 s-1.

We know that energy E=hv where h=Planks constant=6.623x10-34 Js

Therefore minimum energy requred to eject electrons is E=(6.623x10-34 Js)(5.29x1014 s-1)

E=3.50x10-19 J.

b) Given wavelength =245 nm=245x10-9 m.

We know that energy E=hv=hc/ where h=Planks constant= 6.623x10-34 Js and c= velocity of light=3x108 m/s

So kinetic energy E=(6.623x10-4 Js x 3x108 m/s)/245x10-9 m

Therefore Kinetic energy=8.109x10-19 J.

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