Using Einstein's photoelectric equation, kinetic energy of an electron is E when the incident wavelength is λ is E=λhc−ϕ...(1)
When kinetic energy doubles, then, 2E=λ′hc−ϕ...(2)
Subtracting (2)−(1), we have
E=hc(λ′1−λ1)
⇒λ′=Eλ+hchcλ
JEE Main 2022 — Physics Modern Physics
The kinetic energy of emitted electron is E when the light incident on the metal has wavelength λ. To double the kinetic energy, the incident light must have wavelength:
Held on 29 Jul 2022 · Verified 6 Jul 2026.
Eλ−hchc
Eλ+hchcλ
Eλ+hchλ
Eλ−hchcλ
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