Question

The energy of two different electromagnetic radiations are 2eV and 8eV. The ratio of their corresponding wavelengths is
4:1
1:4
5:4
5:2​

Answer 1

Maximum kinetic energy of photo electrons E=hν

incident

−ϕ

where ϕ is work-function.

Case 1 : hν

incident

=1eV and ϕ=0.5eV

⟹ E

1

=1−0.5=0.5eV

Case 1 : hν

incident

=2.5eV and ϕ=0.5eV

⟹ E

2

=2.5−0.5=2eV

Maximum velocity of photo electron v=

m

2E

⟹

v

2

v

1

=

E

2

E

1

=

2

0.5

=

2

1