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?

Let threshold frequency be ${\nu }_0$. Incident frequency $\nu =1.5{\nu }_0$.If the frequency is halved, the new frequency ${\nu }^{\prime }=\frac{1.5{\nu }_0}{2}=0.75{\nu }_0$.Since ${\nu }^{\prime }<{\nu }_0$, the incident frequency is now less than the threshold frequency. Therefore, no photoelectrons will be emitted, and the photoelectric current will be zero, regardless of the intensity.