Rankers Physics

Uncategorized: Practice Problem & Solution

44. Work function of a metal surface is $\phi = 1.5 eV$. If a light of wavelength $5000 \AA$ falls on it then the maximum K.E. of ejected electron will be: (1998)
$1.2 eV$
$0.98 eV$
$0.45 eV$
$0 eV$

Solution Explained:

To solve this problem, we apply the core principles of Uncategorized. Understanding the underlying formula is key to arriving at the correct answer below:

Energy of incident light is $E = \frac{hc}{\lambda} = \frac{12400}{5000} eV = 2.48 eV$. According to Einstein's photoelectric equation, the maximum kinetic energy is $K_{max} = E - \phi = 2.48 eV - 1.5 eV = 0.98 eV$.

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