Question

The work function of a metal is 1.86 eV. Calculate the wavelength of the light that should
be used to eject an electron form the metal.
(a) 740 nm
(b) 668 nm
(c) 106 nm
(d) 488 nm​

Answer 1

ANSWER - 668nm

$e = \frac{12400}{wavelenght}$

here e is the energy which is given 1.86eV

1.8= 12400÷wavelength

wavelength= 12400÷1.86

which is equal to 668nm

Remember in formula wavelength 10*-10