1
JEE Main 2021 (Online) 18th March Evening Shift
+4
-1
In a series LCR circuit, the inductive reactance (XL) is 10$$\Omega$$ and the capacitive reactance (XC) is 4$$\Omega$$. The resistance (R) in the circuit is 6$$\Omega$$. The power factor of the circuit is :
A
$${1 \over 2}$$
B
$${{\sqrt 3 } \over 2}$$
C
$${1 \over {\sqrt 2 }}$$
D
$${1 \over {2\sqrt 2 }}$$
2
JEE Main 2021 (Online) 18th March Evening Shift
+4
-1
The time taken for the magnetic energy to reach 25% of its maximum value, when a solenoid of resistance R, inductance L is connected to a battery, is :
A
infinite
B
$${L \over R}$$ ln10
C
$${L \over R}$$ ln2
D
$${L \over R}$$ ln5
3
JEE Main 2021 (Online) 18th March Morning Shift
+4
-1
In a series LCR resonance circuit, if we change the resistance only, from a lower to higher value :
A
The bandwidth of resonance circuit will increase.
B
The resonance frequency will increase.
C
The quality factor will increase.
D
The quality factor and the resonance frequency will remain constant.
4
JEE Main 2021 (Online) 18th March Morning Shift
+4
-1
An AC source rated 220 V, 50 Hz is connected to a resistor. The time taken by the current to change from its maximum to the rms value is :
A
2.5 ms
B
25 ms
C
2.5 s
D
0.25 ms
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