Question

Einstein's photoelectric equation is $E_k=hv-\varphi$. In this equation $E_k$ refers to :

• A. kinetic energy of all emitted electrons
• B. mean kinetic energy of emitted electrons
• C. maximum kinetic energy of emitted electrons
• D. minimum kinetic energy of emitted electrons

Answer 1

Answer: (C)

maximum kinetic energy of emitted electrons

Using Photoelectric effect

$E_{Incoming}=\varphi +{\left(KE\right)}_{max}$

Hence

${\left(KE\right)}_{max}=E_{Incoming}-\varphi$

$=hv-\varphi$

where ${\left(KE\right)}_{max}$ is the maximum kinetic Energy of emitted electrons from the metal surface