Question

93.
Light of frequendy 1.5 times the threshold
frequency is incident on a photosensitive material
What will be the photoelectric current the
frequency is halved and intensity is double??
please help me out​

Answer 1

Complete Question:

Light of frequency 1.5 times the threshold frequency is incident on a photosensitive material. What will be the photoelectric current the frequency is halved and intensity is doubled?

(1) four times

(2) one-fourth

(3) zero

(4) doubled

Answer:

$\boxed{\mathfrak{(3) \ zero }}$

Explanation:

According to the question incident frequency of light is 1.5 time threshold frequency i.e.

$\rm \nu = \dfrac{3}{2} \nu_o$

When the incident frequency is halved then new incident frequency that is incident on photoelectric material is:

$\rm \nu' = \dfrac{\nu}{2} = \dfrac{3}{4} \nu_o$

So, from this we can conclude that new incident frequency is less than threshold frequency i.e.

$\rm \nu' < \nu_o$

$\therefore$ No photoelectric emission will take place. As, there is no photoelectric emission, photoelectric current will not be generated/produced.

Answer 2

If the frequency is halved and intensity is doubled, the frequency of incident light will become 

15 over 2 space equals space 0.75

 times the threshold 

frequency. Hence, photoelectric current will be zero.