Given figure shows few data points in a photo electric effect experiment for a certain metal.

Question:

Given figure shows few data points in a photo electric effect experiment for a certain metal. The minimum energy for ejection of electron from its surface is : (Plancks constant $h=6.62 \times 10^{-34} \mathrm{~J} . \mathrm{s}$ )

  1. (1) $2.27 \mathrm{eV}$

  2. (2) $2.59 \mathrm{eV}$

  3. (3) $1.93 \mathrm{eV}$

  4. (4) $2.10 \mathrm{eV}$


Correct Option: 1

Solution:

(1) Graph of $V_{s}$ and $f$ given at $B(5.5,0)$

Minimum energy for ejection of electron

$=$ Work function $(\phi)$.

$\phi=h V$ joule or $\phi=\frac{h V}{e} \mathrm{eV}($ for $V=0)$

$\therefore \phi=\frac{6.62 \times 10^{-34} \times 5.5 \times 10^{14}}{1.6 \times 10^{-19}} \mathrm{eV}=2.27 \mathrm{eV}$

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