Given below are two statements: one is labelled as Assertion A an… - Vidyadip

MCQ

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.

Assertion $A$ : The photoelectric effect does not take place, if the energy of the incident radiation is less than the work function of a metal.

Reason $R$ : Kinetic energy of the photoelectrons is zero, if the energy of the incident radiation is equal to the work function of a metal.

In the light of the above statements, choose the most appropriate answer from the options given below

A
Both $A$ and $R$ are correct and $R$ is the correct explanation of $A$
✓
Both $A$ and $R$ are correct but $R$ is not the correct explanation of $A$
C
$A$ is correct but $R$ is not correct
D
$A$ is not correct but $R$ is correct

✓

Answer

Correct option: B.

Both $A$ and $R$ are correct but $R$ is not the correct explanation of $A$

b
To free the electron from metal surface minimum energy required, is equal to the work function of that metal.

So Assertion $A$, is correct.

$h v = w _{0}+ K. E. _{\max }$

if $h v = w _{0}$

$\Rightarrow$ $K.E.$ $_{\text {max }}=0$

Hence reason $R$, is correct, But $R$ is not the correct explanation of $A$.

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