Electromagnetic Waves

JEE Main level, single correct, medium

164 of 165

Question 164 of 165

Two sources of light emit X-rays of wavelength 1 nm and visible light of wavelength 500 nm, respectively. Both the sources emit light of the same power 200 W. The ratio of the number density of photons of X-rays to the number density of photons of the visible light of the given wavelengths is:

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Answer: (A) 1500\dfrac{1}{500}

Ps−{P}_{s}-Power of source
Ps=nhcλ;n{P}_{s}=n\dfrac{hc}{\lambda };n = no. of photons emitted/s
⇒n∝λ⇒n2n1=1/500\Rightarrow n\propto \lambda \Rightarrow \dfrac{{n}_{2}}{{n}_{1}}=1/500

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