JEE Main Physics Class 12 Dual Nature of Matter and Radiation Part 1 Questions

Let work function be W and v1 and v2 be the velocity of electrons for frequencies f1 and f2 .
Using Einstein's photo electric equation for one photodiode, we get
hf1−W=

1

2

mv12 ......(i)
Using Einstein's photo electric equation for another photodiode we get
hf2−W=

1

2

mv22 ......(ii)
Subtracting (ii) from (i) we get
(hf1−W)−(hf2−W)=

1

2

mv12−

1

2

mv22
∴h(f1−f2)=

m

2

(v12−v22)
∴v12−v22=

2h

m

(f1−f2)