A beam of electromagnetic radiation of intensity 6.4 × 10–5 W/cm2 is comprised of wavelength, $\lambda$ = 310 nm. It falls normally on a metal (work function $\phi$ = 2eV) of surface area of 1 cm2. If one in 103 photons ejects an elctron, total number of electrons ejected in 1 s is 10x. (hc = 1240 eVnm, 1eV = 1.6 × 10–19 J), then x is _____.
Answer (integer)
11
Solution
Energy of photon = ${{1240} \over {310}}$ = 4 eV
<br><br>Energy is greater than work function so photoelectric effect will take place.
<br><br>Number of photons = <span style="display: inline-block;vertical-align: middle;">
<div style="text-align: center;border-bottom: 1px solid black;">Intensity</div>
<div style="text-align: center;">Energy of one photon</div>
</span>
<br><br>= ${{6.4 \times {{10}^{ - 5}}} \over {4 \times 1.6 \times {{10}^{ - 19}}}}$ = 10<sup>14</sup>
<br><br>Total number of electrons = ${{{{10}^{14}}} \over {{{10}^3}}}$ = 10<sup>11</sup>
About this question
Subject: Physics · Chapter: Dual Nature of Matter and Radiation · Topic: Photoelectric Effect
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