Question

The energy required to remove an electron from the surface of $Na$ metal is 2.3 eV.
What is the largest wavelength of radiation which can show the photoelectric effect:

• A. $5.3\times {10}^{7}m$
• B. $7.38\times {10}^{7}m$
• C. $5.39\times {10}^{-7}m$
• D. $7.38\times {10}^{-7}m$

Answer 1

The correct option is C $5.39\times {10}^{-7}m$

Given,
The energy required to remove an electron from the surface of Na metal
$=2.3eV$
Again We know,
$E\left(eV\right)=\frac{12400}{\lambda \left(\stackrel{o}{A}\right)}$

$\lambda =\frac{12400}{2.3}=5391.30\stackrel{o}{A}=5.39\times {10}^{-7}m$
Thus the largest wavelength of radiation which can show photoelectric effect = $5.39\times {10}^{-7}m$