- Find i(t) when VS (t) = 100 sin(2510 t).
Zeq = 10 ω i(t) = VS / 10 = 10 sin(2510t).
- What is h(t) in following circuit ?
Step response is given as [1 – e -α t]u(t)
h(t) is an impulse response.
- In a pure parallel LC circuit under resonance condition, current drawn from main supply is
Current in LC circuit is 0 at resonance, because of infinite of parallel LC circuit.
- Z may comprise of following circuit
Series combination of 2.5 mH & 16&mm; F will result in a lossless resonant L-C circuit with constant V.
But parallel combination of 2.5 mH & 16 μ F will result in an exponentially increasing sinusoidal response as shown.
- In a RLC circuit (series) if C is increasing & remaining R & L are constants, then resonant frequency will be
As resonant frequency, f0,
- If all the transmission zeros of a network are at infinity then it is a
lim T(s) = 0
s → ∞
So it will be a low pass filter.
- At lower half power frequency current in series R-L-C circuit has the phase relation with reference to supply voltage as
- A circuit with a resistor, inductor and capacitor in series is resonant of f0 Hz. If all the component values are now doubled the new resonant frequency is
Resonant frequency, f0,
- In a series RLC high Q circuit, the current peaks at a frequency
Now high Q means low R, C & high L.
So bandwidth = f0/Q
Since less bandwidth, hence sharp resonance.
- A sinusoidal voltage V & frequency f connected to a series circuit at variable resistance R and a fixed reactance X. The locus of the tip of the current phase or I as R is varied from zero to infinity is
Above equation is a semicircle equation with radius V/2X.
- In the network shown below, switch S was closed & steady state is a attained. If S is opened at t = 0 & i(t) = 2 cos 100t then what is the value of V ?
Circuit starts oscillating when switch is opened.
Here I = 2, R = 2.5 Ω.
- Circuit shown below has been in steady state when switch S is opened, the current I is given by
When the switch is closed and circuit reached its steady state condition. Since inductor offers short circuit path. So
I = 10 / 1 = 10A
Now, when switch is opened,
- The current i(t) at any instant t in the network shown in the figure will be after closing the switch S at t = 0
The value of the current at t = 0 + and at t = infinity; which should be zero and 10 / 1 = 10 A respectively.
- A series RLC circuit consisting of R = 20 ohms XL = 20 ohms is connected across an ac supply of 200 V rms. The rms voltage across the capacitor is
Z = 20 ohms
I = 200 / 20 = 10 A
V C = –JIXC.
- In a RC circuit consisting R = 10KΩ &phase angle between current &voltage is 45° What is the value of C at Ω = 1 ?
&theata; = tan - 1 (XC /R)
So, XC/R = 1
XC = 10 KΩ
or, 1/ C = 10KΩ.
- In a series RLC circuit the phasor diagram shown as below. Which of following is true regarding phasor diagram for the series RLC circuit ?
Here VC > VL, 1/Ω C > Ω L.
- In a RLC series circuit consisting VR = 3V, V VC=8V & V VL = 4 V, Find the value of source excitation voltage ?
- In a parallel RL Circuit has i = 10A *amp; i VR = 8A. Find the value of current flowing through the inductor ?
- If a capacitor is added in parallel with inductor C in the above question, which draws a current of 6A then i will be
- Consider the following circuit diagram. If R = 25Ω X VL = X VC = 25Ω then what is the value of &theata; j ? [Assuming V as reference phasor]
tan&theata; = X VL/R.
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