Question

A metal was found to have its threshold frequency equal to 10^15 s hertz . If the same metal is irradiated with radiations of frequencies 1.5 * 10^15 herts and 2.5 * 10^15 hertz respectively, the ratio of maximum kinetic energies will be

Answer 1

ANSWER

Let the threshold frequency is = V

0

V

1

=4×10

15

Hz

V

2

=6×10

15

Hz

now (KE)

1

=hV

1

−hV

0

(KE)

2

=hV

2

−hV

0

Given

hV

2

−hV

0

hV

1

−hV

0

=

3

1

3V

1

−3V

0

=V

2

−V

0

2

(3V

1

−V

2

)

=V

0

V

0

=3×10

15

Hz