A metal has work function (binding energy) Φ. Light of frequency ν shines on it. The kinetic energy of ejected electrons follows KE = hν - Φ.
If the frequency is doubled (above the threshold), the kinetic energy of ejected electrons:
- A
Stays the same
- B
Decreases
- Ccheck_circle
Increases by hν (the additional photon energy)
- D
Doubles
Explanation
KE_new - KE_old = h(2ν) - hν = hν, so KE rises by exactly hν of the original photon.