Given, work function Ф =1.9 eV

…… (1)

On comparing the above two equations, we get

…. (3)

We know that λ=c/f……. (4)

Where λ is the wavelength of light,

C is the speed of the light,

f is the frequency of the light.

∴ From eq (3) & (4)we get the value of frequency

∴

Now, from Einstein’s photoelectric equation

….(5)

Where h is the Planck’s constant,

f is the frequency of light,

e is the charge on an electron ,

is the stopping potential,

Ф is the work function.

Putting the values in eq(5) we have,

⇒

⇒

⇒

⇒