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NEET Sample Paper NEET Sample Test Paper-6

  • question_answer
    The power of sound from the speaker of a radio is\[20wW\]. By tunning the knob of volume control the power of sound is increase to\[400m\text{ }W\]. The power increase in dB as compared to the original power is \[(\log \,\,{{10}^{2}}=0.3):\]

    A)  \[1.3\,dB\]                  

    B)  \[3.1\,dB\]

    C)  \[13\,dB\]                   

    D)  \[30.1\,dB\]

    Correct Answer: C

    Solution :

    As,       \[p\propto I\] Increase in power in dB \[S{{L}_{2}}-S{{L}_{1}}=10\log \left( \frac{{{I}_{2}}}{{{I}_{1}}} \right)=10\log \left( \frac{{{p}_{2}}}{{{p}_{1}}} \right)\]                 \[=10\log \left( \frac{400}{20} \right)\]                 \[-10\log 20=12dB\]


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