A metal is illumimated by light of two different wavelength `248nm` and `310 nm` . The maximum speeds of the photoelecrtron corresponding in these wavwlength are ``u_(1) and u_(2)` respectively . If the ratio u_(1) : u_(2) = 2 : 1 ` and `hc = 1240 eVnm `, the work function of the inetial is rearlyA. `3.7 eV`B. `3.2 eV`C. `2.8eV`D. `2.5 eV`

A metal is illumimated by light of two different wavelength `248nm` an

1.	A metal is illumimated by light of two different wavelength `248nm` and `310 nm` . The maximum speeds of the photoelecrtron corresponding in these wavwlength are ``u_(1) and u_(2)` respectively . If the ratio u_(1) : u_(2) = 2 : 1 ` and `hc = 1240 eVnm `, the work function of the inetial is rearlyA. `3.7 eV`B. `3.2 eV`C. `2.8eV`D. `2.5 eV`
Answer» Correct Answer - A `(hC)/(lambda_(1)) W = (1)/(2) mu_(1)^(2)` `and ((hC)/(lambda_(2)) W = (1)/(2) mu_(2)^(2)`` Dividing the above two equation , we get ` ((hC)/(lambda_(1)) - W)/((hC)/(lambda_(2)) - W) ((hC)/(lambda_(1)) - W)/((hC)/(lambda_(2)) - W) (u_(1)^(2)/(u_(2)^(2)` ` :. `((1240)/(248) -W)/((1240)/(310) -W = (4)/(1)` `:. (1240)/(248) -W = (4 xx 1240)/(310) - 4W` `:. W = 3.7 eV`

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