Question

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Answer 1

Maximum Energy = energy of photons - work function
=> maximum Energy = E - ⍉ ......

Answer 2

When a Photon of energy Ep joules strikes the photosensitive surface it collides with the electrons - during this collision the photon gives all of its energy to the electron at the metal surface. here the energy is being divided. .the 1st part of the energy is used for the freeing of the electron and the remaining energy appears as the maximum kinetic energy of the liberated electrons. so the energy required for freeing the electron is the work function of the metal. here given that Φ joules is the work function.

So from the law of conservation of energy :

The Energy possessed by the photon = Energy required for freeing the electron + Maximum kinetic energy of the electron

⇒ Ep = Φ + Maximum kinetic energy of photo electrons

⇒ Maximum kinetic energy of photo electrons = Ep - Φ