Question

A platinum surface having work function 5.63 eV is illuminated by a monochromatic source of 1.6 × 10¹⁵ Hz. What will be the minimum wavelength associated with the ejected electron?

Answer 1

Given: 

`emptyset_0` = 5.63 eV = 5.63 × 1.6 × 10⁻¹⁹ J

v = 1.6 × 10¹⁵ Hz

K.E. = `hv − emptyset_0 = (hc)/lambda`

`lambda = (hc)/(hv - emptyset_0)`

= `(6.63 xx 10^-34 xx 3 xx 10^8)/(6.63 xx 10^-34 xx 1.6 xx 10^15 - 5.63 xx 1.6 xx 10^-19)`

= `(19.89 xx 10^-26)/(1.6 xx 10^-19  (6.63 - 5.63))`

= `(19.89 xx 10^-26)/(1.6 xx 10^-19)`

= 12.4 × 10⁻⁷ m