Ametal with a threshold frequency of 1.40×1015
s
−1
emits an electron with a velocity of 7.79×105
m/s
when radiation of 1.80×1015
s
−1
strikes the metal.

calculate the mass of the electron.

The  mass of the electron is

Explanation:

Photoelectric effect is given by  

where ν0 = threshold frequency of given metal =

ν = given radiation =

v = velocity of emitted electron = given =

m = required mass of electron

h = Plank’s constant =

Substituting the values in the formula  

Solving this we get m =

which is the mass of the electron.