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

From the Einstein's photoelectric equation
Energy of photon = Kinetic energy of photoelectrons + Work function
⇒ Kinetic energy = Energy of Photon − Work Function
Let ϕ0 be the work function of metal and v1 and v2 be the velocity of photoelectrons. Using Einstein's photoelectric equation we have

1

2

mv12=4−ϕ0 ......(i)

1

2

mv22=2.5−ϕ0......(ii)
⇒

1 2 mv12

1 2 mv22

=

4−ϕ0

2.5−ϕ0

⇒(2)2=

4−ϕ0

2.5−ϕ0

⇒10−4ϕ0=4−ϕ0
ϕ0=2eV