Question

Light of frequency $2.5v_0$ is incident on a metal surface of threshold frequency $2v_0,$ It its frequency is halved and intensity is made three times then the new value of photoelectric current will be

• A. Zero
• B. Double
• C. Four times
• D. Six times

Answer 1

The correct option is A Zero

Light with frequencies below a certain cutoff value, called the threshold frequency, would not eject photoelectrons from the metal surface no matter how bright the source.
$h\nu >h{\nu }_o$
Since the frequency is halved we have incident frequency as $1.25{\nu }_o$ and threshold frequency is $2{\nu }_o$.
Hence photocurrent is zero.

So, the answer is option (A).