354817
A bird is singing on a tree and a man is hearing at a distance ' \(r\) ' from the bird. Calculate the displacement of the man towards the bird so that the loudness heard by man increases by 20 \(dB\). [Assume that the motion of man is along the line joining the bird and the man]
354818
The energy per unit area associated with a progressive sound wave will be doubled if:
1 The amplitude of the wave is doubled
2 The amplitude of the wave is increases by \(50 \%\)
3 The amplitude of the wave is increases by \(41 \%\)
4 None of these
Explanation:
\(\dfrac{E}{A}=I\) \(\begin{aligned}& I^{\prime}=2 I \\& A^{\prime 2}=\sqrt{2} A \\& \Delta A=\sqrt{2} A-A=A(\sqrt{2}-1) \\& \dfrac{\Delta A}{A} \%=(\sqrt{2}-1) \times 100=41 \%\end{aligned}\)
PHXI15:WAVES
354819
A person is talking in a small room and the sound intensity level is \(60\;dB\) everywhere within the room. If there are eight people talking simultaneously in the room, what is the sound intensity level?
1 \(69\;dB\)
2 \(60\;dB\)
3 \(81\;dB\)
4 \(74\;dB\)
Explanation:
Let intensity due to a single person \(=I\) then \(10 \log I / I_{0}=60=\beta_{1}\) \(\begin{aligned}& \beta_{2}=10 \log \left(\dfrac{8 I}{I_{0}}\right)=10\left(\log \dfrac{I}{I_{0}}+\log 8\right) \\& =60+10 \log 8=60+30 \log 2=69\end{aligned}\)
PHXI15:WAVES
354820
In the absence of teacher a class of 50 students make a noise level of \(50\;dB\). 50 more students enter the class. Assuming each student on an average produces same intensity of sound then the noise level increases by
1 \(25\;dB\)
2 \(50\;dB\)
3 \(3\;dB\)
4 \(8.33\;dB\)
Explanation:
\(\beta_{1}=10 \log \left(\dfrac{I}{I_{o}}\right)\) After adding 50 more students \(\beta_{2}=10 \log \left(\dfrac{2 I}{I_{o}}\right)\) \(\beta_{2}-\beta_{1}=10 \log \dfrac{2 I}{I_{0}}-10 \log \dfrac{I}{I_{0}}\) \(\Delta \beta = 10\log 2 = 3\,dB\)
354817
A bird is singing on a tree and a man is hearing at a distance ' \(r\) ' from the bird. Calculate the displacement of the man towards the bird so that the loudness heard by man increases by 20 \(dB\). [Assume that the motion of man is along the line joining the bird and the man]
354818
The energy per unit area associated with a progressive sound wave will be doubled if:
1 The amplitude of the wave is doubled
2 The amplitude of the wave is increases by \(50 \%\)
3 The amplitude of the wave is increases by \(41 \%\)
4 None of these
Explanation:
\(\dfrac{E}{A}=I\) \(\begin{aligned}& I^{\prime}=2 I \\& A^{\prime 2}=\sqrt{2} A \\& \Delta A=\sqrt{2} A-A=A(\sqrt{2}-1) \\& \dfrac{\Delta A}{A} \%=(\sqrt{2}-1) \times 100=41 \%\end{aligned}\)
PHXI15:WAVES
354819
A person is talking in a small room and the sound intensity level is \(60\;dB\) everywhere within the room. If there are eight people talking simultaneously in the room, what is the sound intensity level?
1 \(69\;dB\)
2 \(60\;dB\)
3 \(81\;dB\)
4 \(74\;dB\)
Explanation:
Let intensity due to a single person \(=I\) then \(10 \log I / I_{0}=60=\beta_{1}\) \(\begin{aligned}& \beta_{2}=10 \log \left(\dfrac{8 I}{I_{0}}\right)=10\left(\log \dfrac{I}{I_{0}}+\log 8\right) \\& =60+10 \log 8=60+30 \log 2=69\end{aligned}\)
PHXI15:WAVES
354820
In the absence of teacher a class of 50 students make a noise level of \(50\;dB\). 50 more students enter the class. Assuming each student on an average produces same intensity of sound then the noise level increases by
1 \(25\;dB\)
2 \(50\;dB\)
3 \(3\;dB\)
4 \(8.33\;dB\)
Explanation:
\(\beta_{1}=10 \log \left(\dfrac{I}{I_{o}}\right)\) After adding 50 more students \(\beta_{2}=10 \log \left(\dfrac{2 I}{I_{o}}\right)\) \(\beta_{2}-\beta_{1}=10 \log \dfrac{2 I}{I_{0}}-10 \log \dfrac{I}{I_{0}}\) \(\Delta \beta = 10\log 2 = 3\,dB\)
354817
A bird is singing on a tree and a man is hearing at a distance ' \(r\) ' from the bird. Calculate the displacement of the man towards the bird so that the loudness heard by man increases by 20 \(dB\). [Assume that the motion of man is along the line joining the bird and the man]
354818
The energy per unit area associated with a progressive sound wave will be doubled if:
1 The amplitude of the wave is doubled
2 The amplitude of the wave is increases by \(50 \%\)
3 The amplitude of the wave is increases by \(41 \%\)
4 None of these
Explanation:
\(\dfrac{E}{A}=I\) \(\begin{aligned}& I^{\prime}=2 I \\& A^{\prime 2}=\sqrt{2} A \\& \Delta A=\sqrt{2} A-A=A(\sqrt{2}-1) \\& \dfrac{\Delta A}{A} \%=(\sqrt{2}-1) \times 100=41 \%\end{aligned}\)
PHXI15:WAVES
354819
A person is talking in a small room and the sound intensity level is \(60\;dB\) everywhere within the room. If there are eight people talking simultaneously in the room, what is the sound intensity level?
1 \(69\;dB\)
2 \(60\;dB\)
3 \(81\;dB\)
4 \(74\;dB\)
Explanation:
Let intensity due to a single person \(=I\) then \(10 \log I / I_{0}=60=\beta_{1}\) \(\begin{aligned}& \beta_{2}=10 \log \left(\dfrac{8 I}{I_{0}}\right)=10\left(\log \dfrac{I}{I_{0}}+\log 8\right) \\& =60+10 \log 8=60+30 \log 2=69\end{aligned}\)
PHXI15:WAVES
354820
In the absence of teacher a class of 50 students make a noise level of \(50\;dB\). 50 more students enter the class. Assuming each student on an average produces same intensity of sound then the noise level increases by
1 \(25\;dB\)
2 \(50\;dB\)
3 \(3\;dB\)
4 \(8.33\;dB\)
Explanation:
\(\beta_{1}=10 \log \left(\dfrac{I}{I_{o}}\right)\) After adding 50 more students \(\beta_{2}=10 \log \left(\dfrac{2 I}{I_{o}}\right)\) \(\beta_{2}-\beta_{1}=10 \log \dfrac{2 I}{I_{0}}-10 \log \dfrac{I}{I_{0}}\) \(\Delta \beta = 10\log 2 = 3\,dB\)
354817
A bird is singing on a tree and a man is hearing at a distance ' \(r\) ' from the bird. Calculate the displacement of the man towards the bird so that the loudness heard by man increases by 20 \(dB\). [Assume that the motion of man is along the line joining the bird and the man]
354818
The energy per unit area associated with a progressive sound wave will be doubled if:
1 The amplitude of the wave is doubled
2 The amplitude of the wave is increases by \(50 \%\)
3 The amplitude of the wave is increases by \(41 \%\)
4 None of these
Explanation:
\(\dfrac{E}{A}=I\) \(\begin{aligned}& I^{\prime}=2 I \\& A^{\prime 2}=\sqrt{2} A \\& \Delta A=\sqrt{2} A-A=A(\sqrt{2}-1) \\& \dfrac{\Delta A}{A} \%=(\sqrt{2}-1) \times 100=41 \%\end{aligned}\)
PHXI15:WAVES
354819
A person is talking in a small room and the sound intensity level is \(60\;dB\) everywhere within the room. If there are eight people talking simultaneously in the room, what is the sound intensity level?
1 \(69\;dB\)
2 \(60\;dB\)
3 \(81\;dB\)
4 \(74\;dB\)
Explanation:
Let intensity due to a single person \(=I\) then \(10 \log I / I_{0}=60=\beta_{1}\) \(\begin{aligned}& \beta_{2}=10 \log \left(\dfrac{8 I}{I_{0}}\right)=10\left(\log \dfrac{I}{I_{0}}+\log 8\right) \\& =60+10 \log 8=60+30 \log 2=69\end{aligned}\)
PHXI15:WAVES
354820
In the absence of teacher a class of 50 students make a noise level of \(50\;dB\). 50 more students enter the class. Assuming each student on an average produces same intensity of sound then the noise level increases by
1 \(25\;dB\)
2 \(50\;dB\)
3 \(3\;dB\)
4 \(8.33\;dB\)
Explanation:
\(\beta_{1}=10 \log \left(\dfrac{I}{I_{o}}\right)\) After adding 50 more students \(\beta_{2}=10 \log \left(\dfrac{2 I}{I_{o}}\right)\) \(\beta_{2}-\beta_{1}=10 \log \dfrac{2 I}{I_{0}}-10 \log \dfrac{I}{I_{0}}\) \(\Delta \beta = 10\log 2 = 3\,dB\)
354817
A bird is singing on a tree and a man is hearing at a distance ' \(r\) ' from the bird. Calculate the displacement of the man towards the bird so that the loudness heard by man increases by 20 \(dB\). [Assume that the motion of man is along the line joining the bird and the man]
354818
The energy per unit area associated with a progressive sound wave will be doubled if:
1 The amplitude of the wave is doubled
2 The amplitude of the wave is increases by \(50 \%\)
3 The amplitude of the wave is increases by \(41 \%\)
4 None of these
Explanation:
\(\dfrac{E}{A}=I\) \(\begin{aligned}& I^{\prime}=2 I \\& A^{\prime 2}=\sqrt{2} A \\& \Delta A=\sqrt{2} A-A=A(\sqrt{2}-1) \\& \dfrac{\Delta A}{A} \%=(\sqrt{2}-1) \times 100=41 \%\end{aligned}\)
PHXI15:WAVES
354819
A person is talking in a small room and the sound intensity level is \(60\;dB\) everywhere within the room. If there are eight people talking simultaneously in the room, what is the sound intensity level?
1 \(69\;dB\)
2 \(60\;dB\)
3 \(81\;dB\)
4 \(74\;dB\)
Explanation:
Let intensity due to a single person \(=I\) then \(10 \log I / I_{0}=60=\beta_{1}\) \(\begin{aligned}& \beta_{2}=10 \log \left(\dfrac{8 I}{I_{0}}\right)=10\left(\log \dfrac{I}{I_{0}}+\log 8\right) \\& =60+10 \log 8=60+30 \log 2=69\end{aligned}\)
PHXI15:WAVES
354820
In the absence of teacher a class of 50 students make a noise level of \(50\;dB\). 50 more students enter the class. Assuming each student on an average produces same intensity of sound then the noise level increases by
1 \(25\;dB\)
2 \(50\;dB\)
3 \(3\;dB\)
4 \(8.33\;dB\)
Explanation:
\(\beta_{1}=10 \log \left(\dfrac{I}{I_{o}}\right)\) After adding 50 more students \(\beta_{2}=10 \log \left(\dfrac{2 I}{I_{o}}\right)\) \(\beta_{2}-\beta_{1}=10 \log \dfrac{2 I}{I_{0}}-10 \log \dfrac{I}{I_{0}}\) \(\Delta \beta = 10\log 2 = 3\,dB\)
