MCQ
Threshold wavelength for photoelectric effect on sodium is $5000\;\mathring A$. Its work function is
- A$1\;J$
- B$3 \times 10^{-19}\;J$
- ✓$4 \times {10^{ - 19}}J$
- D$2 \times 10^{-19}\;J$
✓
Answer
Correct option: C.
$4 \times {10^{ - 19}}J$
c
(c) ${W_0} = \frac{{hc}}{{{\lambda _0}}} = \frac{{6.625 \times {{10}^{ - 34}} \times 3 \times {{10}^8}}}{{5000 \times {{10}^{ - 10}}}}J = 4 \times {10^{ - 19}}J$
(c) ${W_0} = \frac{{hc}}{{{\lambda _0}}} = \frac{{6.625 \times {{10}^{ - 34}} \times 3 \times {{10}^8}}}{{5000 \times {{10}^{ - 10}}}}J = 4 \times {10^{ - 19}}J$
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