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QJEEAdv21Ph62c3: JEE Advanced 2021 Physics - Class 12 JEEAdv21Ph62c3 Solution: In a photoemission experiment, the maximum kinetic energies of…

In a photoemission experiment, the maximum kinetic energies of photoelectrons from metals P, Q and R are EP, EQ and ER, respectively, and they are related by EP = 2EQ = 2ER. In this experiment, the same source of monochromatic light is used for metals P and Q while a different source of monochromatic light is used for the metal R. The work functions for metals P, Q and R are 4.0 eV, 4.5 eV and 5.5 eV, respectively. The energy of the incident photon used for metal R, in eV, is ___________.

Step-by-Step Verified Solution

EP = 2EQ = 2ER = E(assume)

For metal P and Q,

E1 - 4 = EP = E ……..(1)

E1 - 4.5 = EA = E/2 ……..(2)

Subtracting equation (2) from (1), we get

E/2 = 0.5

For metal R

E2 - 5.5 = ER = E/2 = 0.5

⇒ E2 = 6

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