The work function for gold is 5.1 eV. (a) Convert the value of the work function

Question

The work function for gold is 5.1 eV.
(a) Convert the value of the work function from electron volts to joules.
J

(b) Find the cutoff frequency for gold.
Hz

(c) What maximum wavelength of light incident on gold releases photoelectrons from the gold's surface?
m

(d) If light of energy 7.5 eV is incident on gold, what is the maximum kinetic energy of the ejected photoelectrons? Give the answer in electron volts.
eV

(e) For photons of energy 7.5 eV, what stopping potential would be required to arrest the current of photoelectrons?

Explanation / Answer

( a ) 

E = 5.1 eV ; 

E = 5.1 * 1.6 e -19  J  

E = 8.16 e -19 J  <----------ans

( b ) 

hv = 8.16 e -19  ; 

6.626 e -34 v = 8.16 e -19 

or v  = 1.231 e 15 Hz   <------------ans

( c ) 

= c / v ; 

= c / [ 1.231 e 15 ] ; 

= 2.434 e -7 m  <------------ans

( d ) 

E2 - E1 = K ; 

( 7.5 - 5.1 ) e V = K ; 

2.4 eV = K  <----------------ans   

( e ) 

e ( V0 ) = K ; 

1.6 e -19  * V0  = 6 * 1.6 e -19   

V0 = 2.4 V   <---------------ans

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