Question

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

• A. One Fourth
• B. Zero
• C. Double
• D. Four Times

Answer 1

The correct option is B Zero

Let the threshold frequency for emission of photoelectrons be ${\nu }_0$
Given that the incident frequency,
${\nu }_1=1.5{\nu }_0$
Now after the incident frequency is reduced to half of initial value,
${\nu }_2=0.75{\nu }_0$
Thus, ${\nu }_2<{\nu }_0$
$\text{Incident Frequency}<\text{Threshold frequency}$
Therefore, no photoelectrons will be emitted.
$\Rightarrow$ $\text{Incident Frequency}>\text{Threshold frequency}$ then,
$n\propto I$
${}^{\prime }{n}^{\prime }$ is the number of emitted photoelectrons
$\therefore$Photoelectric current $\left(I\right)$ will be ${}^{\prime }{\text{Zero}}^{\prime }$