Question

When a metallic surface is illuminated with radiation of wavelength λ, the stopping potential is V. If the same surface is illuminated with radiation of wavelength 2λ, the stopping potential is V4. The threshold wavelength for the metallic surface is :

Answer 1

Answer:

We know that:

eV=

λ

hc

−ϕ ........ (1)

4

eV

=

2λ

hc

−ϕ ........ (2)

From equations (1) and (2), we get:

⇒4=

2λ

1

−

λ

0

1

λ

1

−

λ

0

1

⇒λ

0

=3λ