In photoelectric effect, if the energy required to overcome the attractive forces on the electron, (work functions) of Li, Na and $ \mathrm{Rb} $ are $ 2.41 \mathrm{eV}, 2.30 \mathrm{eV} $ and $ 2.09 \mathrm{eV} $ respectively, the work function of ' $ \mathrm{K} $ ' could approximately be in eV

Question

In photoelectric effect, if the energy required to overcome the attractive forces on the electron, (work functions) of Li, Na and $ \mathrm{Rb} $ are $ 2.41 \mathrm{eV}, 2.30 \mathrm{eV} $ and $ 2.09 \mathrm{eV} $ respectively, the work function of ' $ \mathrm{K} $ ' could approximately be in eV, $ 2.52 $, $ 2.20 $, $ 2.35 $, $ 2.01 $

MARKS App · Accepted Answer

As the size of atom (element) increases, energy required to overcome the attractive force on outermost electron decreases. Li, Na, K and Rb are the members of same group and have the following order of size L i N a K R b Thus, the energy in case of K is intermediate of Rb and Na, i.e., 2.30 K > 2.09 or the energy for K is 2.20 eV.

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