Electromagnetic Induction & AC · JEE Main previous year questions

2017 2 questions

1. Q392017 · 9 Apr 2017 · Shift 1

   A sinusoidal voltage of peak value 283 V and angular frequency 320/s is applied to a series LCR circuit. Given that R=$5\Omega$, L=25 mH and C=1000 $\mu \mathrm{F}$. The total impedance, and phase difference between the voltage across the source and the current will respectively be :

   1. A.$10\Omega \text{and}{\tan }^{-1}\left(\frac{5}{3}\right)$
   2. B.$7\Omega \text{and}45^{\circ }$
   3. C.$10\Omega \text{and}{\tan }^{-1}\left(\frac{8}{3}\right)$
   4. D.$7\Omega \text{and}{\tan }^{-1}\left(\frac{5}{3}\right)$
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   Answer: B

2. Q482017 · 8 Apr 2017 · Shift 1

   A small circular loop of wire of radius a is located at the centre of a much larger circular wire loop of radius b. The two loops are in the same plane. The outer loop of radius b carries an alternating current $\mathrm{I}={\mathrm{I}}_o\cos (\omega t)$. The emf induced in the smaller inner loop is nearly :

   1. A.$\frac{\pi {\mu }_o{\mathrm{I}}_o}{2}\cdot \frac{a^2}{b}\omega \sin (\omega t)$
   2. B.$\frac{\pi {\mu }_o{\mathrm{I}}_o}{2}\cdot \frac{a^2}{b}\omega \cos (\omega t)$
   3. C.$\pi {\mu }_o{\mathrm{I}}_o\frac{a^2}{b}\omega \sin (\omega t)$
   4. D.$\frac{\pi {\mu }_o{\mathrm{I}}_o{b}^2}{a}\omega \cos (\omega t)$
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   Answer: A