Dual Nature of Matter

JEE Main level, single correct, medium

125 of 200

Question 125 of 200

Two sources of light emit with a power of 200W200W. The ratio of number of photons of visible light emitted by each source having wavelengths 300nm300nm and 500nm500nm respectively, will be :

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Answer: (D) 3:53:5

Let n1{n}_{1} and n2{n}_{2} be the number of photons coming out from the first and the second source of light respectively per second.
So, for the first source,
n1×hcλ1=200...(1){n}_{1}\times \dfrac{hc}{{\lambda }_{1}}=200...\left(1\right)
And, for the second source,
n2×hcλ2=200...(2){n}_{2}\times \dfrac{hc}{{\lambda }_{2}}=200...\left(2\right)
From equations (1) and (2), it implies that
n1n2=λ1λ2=300500⇒n1n2=35\dfrac{{n}_{1}}{{n}_{2}}=\dfrac{{\lambda }_{1}}{{\lambda }_{2}} =\dfrac{300}{500} \Rightarrow \dfrac{{n}_{1}}{{n}_{2}}=\dfrac{3}{5}

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