Question

The radiation of wavelength 300nmis incident on a silver surface .will photoelectrons be observed (the work function of silver =4.7eV) 12th physics​

Answer 1

Explanation:

Einstein's equation for photoelectric effect is given by, eV

0

=E−W

In first case: eV

0

=7.7eV, where V

0

is the cut-off potential and

W=4.7eV, work function of silver metal.

So, Energy of photon is E

1

=E=eV

0

+W=7.7+4.7=12.4eV

We know that E=

λ

hc

If E

2

is the photon energy in the second case,

E

1

E

2

=

λ

2

λ

1

=

200nm

100nm

=0.5

so E

2

=0.5E

1

=0.5(12.4)=6.2eV

If V

02

is the cut-off potential in the second case, eV

01

=E

2

−W (as same metal for both case so W is same for both case)

or eV

02

=6.2−4.7=1.5eV

or V

02

=1.5V