1
JEE Main 2021 (Online) 26th August Morning Shift
+4
-1
An inductor coil stores 64 J of magnetic field energy and dissipates energy at the rate of 640 W when a current of 8A is passed through it. If this coil is joined across an ideal battery, find the time constant of the circuit in seconds :
A
0.4
B
0.8
C
0.125
D
0.2
2
JEE Main 2021 (Online) 26th August Morning Shift
+4
-1
A series LCR circuit driven by 300 V at a frequency of 50 Hz contains a resistance R = 3 k$$\Omega$$, an inductor of inductive reactance XL = 250 $$\pi$$$$\Omega$$ and an unknown capacitor. The value of capacitance to maximize the average power should be : (Take $$\pi$$2 = 10)
A
4 $$\mu$$F
B
25 $$\mu$$F
C
400 $$\mu$$F
D
40 $$\mu$$F
3
JEE Main 2021 (Online) 27th July Evening Shift
+4
-1
A 100$$\Omega$$ resistance, a 0.1 $$\mu$$F capacitor and an inductor are connected in series across a 250 V supply at variable frequency. Calculate the value of inductance of inductor at which resonance will occur. Given that the resonant frequency is 60 Hz.
A
0.70 H
B
70.3 mH
C
7.03 $$\times$$ 10$$-$$5 H
D
70.3 H
4
JEE Main 2021 (Online) 27th July Morning Shift
+4
-1
A 0.07 H inductor and a 12$$\Omega$$ resistor are connected in series to a 220V, 50 Hz ac source. The approximate current in the circuit and the phase angle between current and source voltage are respectively. [Take $$\pi$$ as $${{22} \over 7}$$]
A
8.8 A and $${\tan ^{ - 1}}\left( {{{11} \over 6}} \right)$$
B
88 A and $${\tan ^{ - 1}}\left( {{{11} \over 6}} \right)$$
C
0.88 A and $${\tan ^{ - 1}}\left( {{{11} \over 6}} \right)$$
D
8.8 A and $${\tan ^{ - 1}}\left( {{{6} \over 11}} \right)$$
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