JEE Mains · Physics · STD 12 - Dual nature of radiation and matter
- JEE Mains 2024
- Hard
- Numerical
A point source is emitting sound waves of intensity \(16 \times 10^{-8} \mathrm{Wm}^{-2}\) at the origin. The difference in intensity (magnitude only) at two points located at a distances of \(2 \mathrm{~m}\) and \(4 \mathrm{~m}\) from the origin respectively will be _______ \(\times 10^{-8} \mathrm{Wm}^{-2}\)
Pick an option to check your answer.
Answer & Solution
Correct Answer
(A) \(3\)
Step-by-step Solution
Detailed explanation
Correct answer is : \(3\)
We know for point source, \(I \propto \frac{1}{r^2}=\frac{K}{4 \pi r^2}\)
\(r_1=2 m, r_2=4 m=2 r_1 \)
\(I_0=16 \times 10^{-8} W / m ^2\)
at \(2 m\),
\(I_1=\frac{I_0}{(2)^2}=\frac{16 \times 10^{-8}}{4} \)
\(I_1=4 \times 10^{-8} \)
\( I_2=\frac{I_0}{4_2}=\frac{16 \times 10^{-8}}{16}=10^{-8} \)
\(\left|I_2-I_1\right|=3 \times 10^{-8} W / m ^2, x=3\)

We know for point source, \(I \propto \frac{1}{r^2}=\frac{K}{4 \pi r^2}\)
\(r_1=2 m, r_2=4 m=2 r_1 \)
\(I_0=16 \times 10^{-8} W / m ^2\)
at \(2 m\),
\(I_1=\frac{I_0}{(2)^2}=\frac{16 \times 10^{-8}}{4} \)
\(I_1=4 \times 10^{-8} \)
\( I_2=\frac{I_0}{4_2}=\frac{16 \times 10^{-8}}{16}=10^{-8} \)
\(\left|I_2-I_1\right|=3 \times 10^{-8} W / m ^2, x=3\)

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