What is the threshold frequency for sodium metal if a photon with frequency 6.66 × 1014 s−1 ejects an electron with 7.74 × 10−20 J kinetic energy? Will the photoelectric effect be observed if sodium is exposed to orange light?

Threshold frequency for sodium metal is

Explanation:

We know, relation between  threshold frequency , kinetic energy and frequency is given by :

Here h is plank's constant and is threshold frequency .

Given :

Frequency of photon ,

Kinetic energy of electron ,

Putting all these value in above equation we get :

Hence , this is the required solution .