The number of photons emitted by a 10,W bulb | vedclass

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Question

(A) The total energy $E$ emitted by the bulb is given by $E = P 	imes t,$ where $P = 10\,W$ and $t = 10\,s.$$E = 10 	imes 10 = 100\,J.$The energy of

Vedclass · Accepted Answer

$5.05 	imes 10^{20}$

Vedclass · Answer

(A) The total energy $E$ emitted by the bulb is given by $E = P 	imes t,$ where $P = 10\,W$ and $t = 10\,s.$$E = 10 	imes 10 = 100\,J.$The energy of a single photon is given by $E_{ph} = \frac{hc}{\lambda}.$Given $h = 6.63 	imes 10^{-34}\,J\cdot s,$ $c = 3 	imes 10^8\,m/s,$ and $\lambda = 1000 	imes 10^{-10}\,m = 10^{-7}\,m.$$E_{ph} = \frac{6.63 	imes 10^{-34} 	imes 3 	imes 10^8}{10^{-7}} = 19.89 	imes 10^{-19}\,J.$The number of photons $n$ is given by $n = \frac{E}{E_{ph}}.$$n = \frac{100}{19.89 	imes 10^{-19}} \approx 5.027 	imes 10^{20}.$Rounding to the nearest provided option,the correct value is $5.05 	imes 10^{20}.$

The number of photons emitted by a $10\,W$ bulb in $10\,s,$ if the wavelength of light is $1000\,\mathring{A},$ is:

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