BHU PMT BHU PMT (Screening) Solved Paper-2007

  • question_answer
    The reactance of a coil when used in the AC power supply (220 V, 50 cycle/s) is\[50\,\Omega \]. The inductance of the coil is nearly

    A)  0.16 H                                  

    B)  0.22 H

    C)   2.2 H                                   

    D)  1.6 H

    Correct Answer: A

    Solution :

                     In a coil the product of angular frequency\[(\omega )\]and inductance (L) is known as the reactance of the coil or inductive reactance and is denoted by\[{{X}_{L}}\]. Thus,       \[{{X}_{L}}=\omega L=2\pi fL\] where\[f\]is frequency. Putting the numerical values from the. question, we have                 \[{{X}_{L}}=50\,\Omega ,f=50\,cps\] \[\therefore \]  \[L=\frac{{{X}_{L}}}{\omega }=\frac{{{X}_{L}}}{2\pi f}=\frac{50}{2\pi \times 50}\]                 \[=\frac{1}{2\times 3.14}=0.16\,H\]


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