Question

radiation of wavelength 3000 angstroms is required to remove an electron from a metal atom if radiation of wavelength 2000 angstrom is allowed to impact on a metal surface the kinetic energy of the emitted electron in kilojoules per mole​

Answer 1

Answer:

THE ANSWER TO THIS QUESTION IS KINETIC ENERGY IN KILO JOULES IS 3.3125×$10^{-22}$

Explanation:

From the concept of "PHOTO ELECTRIC EFFECT"  we can understand that the maximum wavelength required to remove an electron from the metal surface is called the threshold wavelength and in this problem it is mentioned as 3000 angstroms.

FROM THE PHOTOELECTRIC EQUATION

hc/λ -hc/λ0 = kinetic energy of the resulting electrons  

where λ is the incident frequency and

           λ0 is the threshold frequency

Calculating,

Value of Planck's constant h=6.625×$10^{-34}$ SI UNITS

Value of c=speed of light=3×$10^{8}$ SI UNITS

Kinetic energy of resulting electrons=6.625×$10^{-34}$×3×$10^{8}$($\frac{1}{2000}$-$\frac{1}{3000}$)×$10^{10}*$$10^{-3}$

Calculating the above expression we obtain kinetic energy in kilo joules as $10^{-19}$×0.0033125

Answer 2

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