1
JEE Main 2018 (Online) 16th April Morning Slot
+4
-1
A power transmission line feeds input power at 2300 V to a step down transformer with its primary windings having 4000 turns, giving the output power at 230 V. If the current in the primary of the transformer is 5 A, and its efficiency is 90%, the output current would be ;
A
50 A
B
45 A
C
25 A
D
20 A
2
JEE Main 2018 (Offline)
+4
-1
In an a.c. circuit, the instantaneous e.m.f. and current are given by
e = 100 sin 30 t
i = 20 sin $$\left( {30t - {\pi \over 4}} \right)$$
In one cycle of a.c., the average power consumed by the circuit and the wattless current are, respectively
A
50, 0
B
50, 10
C
$${{1000} \over {\sqrt 2 }},10$$
D
$${{50} \over {\sqrt 2 }}$$
3
JEE Main 2018 (Offline)
+4
-1
Out of Syllabus
For an RLC circuit driven with voltage of amplitude vm and frequency $${\omega _0}$$ = $${1 \over {\sqrt {LC} }}$$ the current exhibits resonance. The quality factor, Q is given by :
A
$${{CR} \over {{\omega _0}}}$$
B
$${{{\omega _0}L} \over R}$$
C
$${{{\omega _0}R} \over L}$$
D
$${R \over {\left( {{\omega _0}C} \right)}}$$
4
JEE Main 2018 (Online) 15th April Morning Slot
+4
-1
An ideal capacitor of capacitance $$0.2\,\mu F$$ is charged to a potential difference of $$10$$ $$V.$$ The charging battery is then disconnected. The capacitor is then connected to an ideal inductor of self inductance $$0.5$$ $$mH.$$ The current at a time when the potential difference across the capacitor is $$5$$ $$V,$$ is :
A
$$0.34\,\,A$$
B
$$0.25\,\,A$$
C
$$0.17\,\,A$$
D
$$0.15\,\,A$$
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