When a certain metal was irradiated with light of frequency 1.6 × 1016 Hz, the photoelectrons emitted had twice the kinetic energy as the photoelectrons emitted when the same metal was irradiated with light of frequency 1.0 × 1016 Hz. Calculate the threshold frequency (v0) for the metal.
4 × 1015 Hz
From Einstein's equation, we know
KE = hν - hν0
KE2 = KE12
Now, KE1 = h(ν − ν0)
KE2 = h(ν2 − ν0)
⇒ ν2 −ν0ν1 −ν0 = 12
⇒1 × 1016 − ν01.6 × 1016 − ν0 = 12
⇒ Thethresholdfrequency ν0 = 4 × 1015 Hz