2. Sample Papers
  3. JEE Main & Advanced

JEE Main & Advanced Sample Paper JEE Main Sample Paper-43

  • question_answer
    \[\sum\limits_{i=1}^{n}{{{a}_{i}}=0,}\] where \[|{{a}_{i}}|\,=1,\,\,\forall \,i,\] then the value of \[\sum\limits_{1\le i\le }{\,\sum\limits_{j<n}{{{a}_{i}}\cdot {{a}_{j}}}}\] is

    A)  \[-\frac{n}{2}\]                                 

    B)  \[-n\]

    C)  \[\frac{n}{2}\]                                   

    D)  \[n\]

    Correct Answer: A

    Solution :

     \[T=\frac{2\pi }{\omega }\] \[\Rightarrow \] \[\xi =\frac{4BA\omega }{2\pi }=\frac{2BA\omega }{\pi }\] \[I=\frac{P}{4\pi {{r}^{2}}}=\frac{60}{4\pi \times {{4}^{2}}}W/{{m}^{2}}\] \[{{P}_{1}}=I\times \frac{\pi {{d}^{2}}}{4}\] \[{{P}_{1}}=\frac{60}{4\pi \times {{4}^{2}}}\times \frac{\pi \times {{(2\times {{10}^{-3}})}^{2}}}{4}\] \[=9.375\times {{10}^{-7}}\,J/s\]


You need to login to perform this action.
You will be redirected in 3 sec spinner