Dual Nature of Radiation and Matter - Result Question 70
74. The wavelength of a $1 keV$ photon is $1.24 \times 10^{-9} m$. What is the frequency of $1 MeV$ photon?
[1991]
(a) $1.24 \times 10^{15}$
(b) $2.4 \times 10^{20}$
(c) $1.24 \times 10^{18}$
(d) $2 \times 4 \times 10^{23}$
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Answer:
Correct Answer: 74. (b)
Solution:
- (b) Here, $\frac{hc}{\lambda}=10^{3} eV$ and $h \nu=10^{6} eV$
Hence, $v=\frac{10^{3} c}{\lambda}=\frac{10^{3} \times 3 \times 10^{8}}{1.24 \times 10^{-9}}$
$=2.4 \times 10^{20} Hz$
