Question on kinetic energy

[Emma Randolph 1J]

For the photoelectric effect equation, is the kinetic energy always equal to 1/2mv^2 or can that be used for any part of the equation like the energy of the photon?

[Nada AbouHaiba 1I]

That equation is just for the kinetic energy of the ejected electron
You can't use that equation for the energy of a photon because mass is required and a photon has no measurable mass
hope this helped:)

[Brian Kwak 1D]

Thank you for the clarification.

[JiangJC Dis2K]

No. 1/2mv^2 can only be used for particles that have mass and velocity (essentially particles in motion). This cannot be applied to photons because they have no rest mass. Therefore, the equation hc/E is used instead of h/p.

[Mikka Hoffman 1C]

Kinetic energy of the ejected photon is given by 1/2mv^2 and the energy of the photon is given by the equation E=hv

[Sydney Stump]

It is true that Ek is always equal to 1/2mv^2 - but it can also be used to find the energy of a photon in the sense that Ephoton = Ekinetic + Threshold Energy.