The energy required to remove an electron from the surface of Sodium metal is 2.3 e V . What is the longest…

The energy required to remove an electron from the surface of Sodium metal is  2.3 eV. What is the longest wavelength of radiation with which it can show photoelectric effect?
  1. 5.4×10-17 m
  2. 5.4×10-8 m
  3. 5.4×10-7 m
  4. 5.4×10-9 m

Solution

Energy required to show photo emission =2.3 eV

=2.3 ×1.6×10-19 J 

Thus E = hcλ  or  λ=hcE=6.626×10-34×3×1082.3×1.6×10-19

= 5.4 ×10-7 m.

Thus, longest wavelength to show photoelectric effect =5.4 ×10-7 m.

Asked in: JEE-TOPICTESTS-CHEMISTRY

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