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Question

Physics Question on Photoelectric Effect

The number of photons of wavelength of 540 nm emitted per second by an electric bulb of power 100 W is (Given h=6×10−34 J s)h ={ 6 \times 10^{-34} \,J \, s})

A

100

B

1000

C

3×10203 \times 10^{20}

D

3×10183 \times 10^{18}

Answer

3×10203 \times 10^{20}

Explanation

Solution

Power = nhcλ\frac{nhc}{\lambda}
⇒  100=n×(6×10−34)(3×108)540×10−9\Rightarrow \:\: 100 = \frac{n \times ( 6 \times 10^{-34} )(3 \times 10^8)}{540 \times 10^{-9}}
⇒   n=100×540×10−918×10−26=3×1020\Rightarrow \:\:\: n = \frac{ 100 \times 540 \times 10^{-9}}{18 \times 10^{-26}} = 3 \times 10^{20}