From Einstein’s photoelectric equation, we get
= ϕ +
eV0 where ϕ is the work function and
V0 is the stopping potential:
V0 =
− On comparing with y = mx + c, we get the slope
m =
= tan θ
• For metal (1):
=
= 0.001
• For metal (2):
=
= 0.002
• For metal (3):
=
= 0.004
Therefore,
ϕ1:ϕ2"ϕ3 = 1 : 2 : 4
For metal (2), the threshold is
λ02 =
=
= 500 nm
For metal (3), the threshold is
λ03 =
=
= 250 nm
(a)
λviolet = 400 nm <
λ02.
(b)
λviolet ejects photoelectrons from metal (2).
(c)
λviolet = 400 nm <
λ03.
(d)
λviolet cannot eject photoelectrons from metal (3).