1
JEE Main 2014 (Offline)
+4
-1
In the circuit shown here, the point $$'C'$$ is kept connected to point $$'A'$$ till the current flowing through the circuit becomes constant. Afterward, suddenly, point $$'C'$$ is disconnected from point $$'A'$$ and connected to point $$'B'$$ at time $$t=0.$$ Ratio of the voltage across resistance and the inductor at $$t=L/R$$ will be equal to : A
$${e \over {1 - e}}$$
B
$$1$$
C
$$-1$$
D
$${{1 - e} \over e}$$
2
JEE Main 2013 (Offline)
+4
-1
In an $$LCR$$ circuit as shown below both switches are open initially. Now switch $${S_1}$$ is closed, $${S_2}$$ kept open. ($$q$$ is charge on the capacitor and $$\tau$$ $$=RC$$ is Capacitance time constant). Which of the following statement is correct ? A
Work done by the battery is half of the energy dissipated in the resistor
B
$$t = \,\tau ,\,q = CV/2$$
C
At $$t = \,2\tau ,\,q = CV\left( {1 - {e^{ - 2}}} \right)$$
D
At $$t = \,2\tau ,\,q = CV\left( {1 - {e^{ - 1}}} \right)$$
3
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
$$1.3 \times {10^4}\,\Omega$$
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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