Question

4)8
32.Electrons are emitted with zero velocity from a metal suylace when it is exposed to radiation of
wavelength 4000 A'. The threshold frequency is
1) 5 x10 sec
sec
33n element 7
2) 7.5 x1014
-1
101 sen
4) 7.5 x1024
bast bon dio​

Answer 1

Explanation:

Since, K.E is zero, the energy of radiation is equal to the work function of the metal. Also, the threshold frequency is equal to the frequency of radiation.

The threshold frequency is

ν

o

=ν=

λ

c

=

6800×10

−10

3.0×10

8

m/s

m

=4.41×10

14

/s.

The work function is

hν

0

=6.626×10

−34

×4.41×10

14

=2.92×10

−19

J.