1
AIEEE 2011
+4
-1
A fully charged capacitor $$C$$ with initial charge $${q_0}$$ is connected to a coil of self inductance $$L$$ at $$t=0.$$ The time at which the energy is stored equally between the electric and the magnetic fields is :
A
$${\pi \over 4}\sqrt {LC}$$
B
$$2\pi \sqrt {LC}$$
C
$$\sqrt {LC}$$
D
$$\pi \sqrt {LC}$$
2
AIEEE 2011
+4
-1
A resistor $$'R'$$ and $$2\mu F$$ capacitor in series is connected through a switch to $$200$$ $$V$$ direct supply. Across the capacitor is a neon bulb that lights up at $$120$$ $$V.$$ Calculate the value of $$R$$ to make the bulb light up $$5$$ $$s$$ after the switch has been closed. $$\left( {{{\log }_{10}}2.5 = 0.4} \right)$$
A
$$1.7 \times {10^5}\,\Omega$$
B
$$2.7 \times {10^6}\,\Omega$$
C
$$3.3 \times {10^7}\,\Omega$$
D
$$1.3 \times {10^4}\,\Omega$$
3
AIEEE 2010
+4
-1
In a series $$LCR$$ circuit $$R = 200\Omega$$ and the voltage and the frequency of the main supply is $$220V$$ and $$50$$ $$Hz$$ respectively. On taking out the capacitance from the circuit the current lags behind the voltage by $${30^ \circ }.$$ On taking out the inductor from the circuit the current leads the voltage by $${30^ \circ }.$$ The power dissipated in the $$LCR$$ circuit is
A
$$305$$ $$W$$
B
$$210$$ $$W$$
C
$$zero$$ $$W$$
D
$$242$$ $$W$$
4
AIEEE 2010
+4
-1
In the circuit shown below, the key $$K$$ is closed at $$t=0.$$ The current through the battery is
A
$${{V{R_1}{R_2}} \over {\sqrt {R_1^2 + R_2^2} }}$$ at $$t=0$$ and $${V \over {{R_2}}}$$ at $$t = \infty$$
B
$${V \over {{R_2}}}$$ at $$\,t = 0$$ and $${{V\left( {{R_1} + {R_2}} \right)} \over {{R_1}{R_2}}}$$ at $$t = \infty$$
C
$${V \over {{R_2}}}$$ at $$\,t = 0$$ and $${{V{R_1}{R_2}} \over {\sqrt {R_1^2 + R_2^2} }}$$ at $$t = \infty$$
D
$${{V\left( {{R_1} + {R_2}} \right)} \over {{R_1}{R_2}}}$$ at $$t=0$$ and $${V \over {{R_2}}}$$ at $$t = \infty$$
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Medical
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