Light of wavelength 380 nm is used in a photoelectric effect experiment a) If 13

Question

Light of wavelength 380 nm is used in a photoelectric effect experiment

a) If 13×1015 photons are emitted per second by this light source, calculate its
power (in watts).

I got 0.00676W for this answer, but I'm not sure if that's correct.

b) It is found that on metal X (an unknown) only light of wavelength less than 380 nm ejects photo-electrons. Calculate the work function of this metal, in eV.

c) When on metal X one uses instead light of wavelength 240 nm, what is the
maximum kinetic energy, in eV, of the photo-electrons that are being ejected?

Will rate!

Explanation / Answer

E = n hv ;

E = n h c / ;

E = 13 e15 * 6.626 e -34 * 299792458 / [ 380 e -9 ]

E = 6.795 e-3 W <-----------ans

( b )

E = hv ;

E = h c / ;

E = 6.626 e -34 * 299792458 / [380 e - 9]

E = 5.227 e -19 J ;

E ( in eV ) = 5.227 e -19 / [ 1.6 e -19 ]

E ( in eV ) = 3.267 eV <-----------ans

( c )

K = hv - hv0 ;

K = h c ( 1/ - 1 / 0 ) ;

K = h c ( 1/ 240e-9 - 1 / 380e-9 ) ;

K = 3.049 e -19 J ;

K ( in eV ) = 3.049 e -19 / [ 1.6 e -19 ]

K ( in eV ) = 1.9058 eV <------------ans

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