Question

A metallic plate of surface charge density + 2${ϵ}_0$ (in SI units) is irradiated with photons of wavelength 620 nm. The work function of metal is 1.5 eV. What maximum distance from the metal plate can the ejected photoelectrons go before turning back? (Assume photoelectrons to be emitted perpendicular to the plate)?

• A. No photoelectrons will be emitted
• B. Photoelectrons will not turn back at all
• C. $\frac{1}{4}m$
• D. $\frac{1}{2}m$

Answer 1

The correct option is A No photoelectrons will be emitted

$h\upsilon =E_K+\varphi$ $\varphi =$ Work function.

$\therefore$ $h\upsilon =6.626\times {10}^{-34}\times 620\times {10}^{-9}$

& $\varphi =1.5\times 1.6\times {10}^{-19}$

As, $\varphi >h\upsilon$ ;

No electrons will leave the plate (electric) given here.