What is Ac circuit: Definition and 199 Discussions
A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The reverse operation is performed by the inverter.
The process is known as rectification, since it "straightens" the direction of current. Physically, rectifiers take a number of forms, including vacuum tube diodes, wet chemical cells, mercury-arc valves, stacks of copper and selenium oxide plates, semiconductor diodes, silicon-controlled rectifiers and other silicon-based semiconductor switches. Historically, even synchronous electromechanical switches and motors have been used. Early radio receivers, called crystal radios, used a "cat's whisker" of fine wire pressing on a crystal of galena (lead sulfide) to serve as a point-contact rectifier or "crystal detector".
Rectifiers have many uses, but are often found serving as components of DC power supplies and high-voltage direct current power transmission systems. Rectification may serve in roles other than to generate direct current for use as a source of power. As noted, detectors of radio signals serve as rectifiers. In gas heating systems flame rectification is used to detect presence of a flame.
Depending on the type of alternating current supply and the arrangement of the rectifier circuit, the output voltage may require additional smoothing to produce a uniform steady voltage. Many applications of rectifiers, such as power supplies for radio, television and computer equipment, require a steady constant DC voltage (as would be produced by a battery). In these applications the output of the rectifier is smoothed by an electronic filter, which may be a capacitor, choke, or set of capacitors, chokes and resistors, possibly followed by a voltage regulator to produce a steady voltage.
More complex circuitry that performs the opposite function, that is converting DC to AC, is called an inverter.
By Faraday's law
$$-V(t)+I(t)R+\frac{q(t)}{C}=-L\dot{I}(t)\tag{1}$$
$$\dot{I}+\frac{R}{L}I+\frac{1}{LC}q=\frac{V(t)}{L}\tag{2}$$
Here we can either form a differential equation in ##q(t)## or we can differentiate and form one in ##I(t)##.
These equations are...
I tried to start by assuming that we need to integrate something over 1 period (2pi). Therefore, we need i(t)^2 R integrated over something. From there, I recognized that this is an underdamped model since R/2L < 1/sqrt(LC). I believe that i(t) can be represented by i(t) = e^(-at)[A_1 cos(w_d t)...
When I write ##X_C=\frac ui=\frac{U_\mathrm m \sin \omega t}{I_\mathrm m \sin \left(\omega t+\frac{\pi}{2}\right)}##, it should be ##\frac{U_\mathrm m}{I_\mathrm m}##, but it isn't. Why?
Hi first time using this forum, I have some homework that I am entirely stuck on, can anyone help me with this question? I understand the placement of nodes, and that I need to convert complex numbers, but apart from that I have no idea what direction that I'm supposed to take in this. I don't...
im kinda confused on why can't you just use the formula P=I^2R.
Can you just use Vrms or Vamp (not sure which one is it) and the value of R which is 105Ω to solve for I
Then just plug it in the formula P=I^2R. But when i did that it the wrong answer so is this formula don't work for AC...
I am trying to figure something out, but I am in the first step and just trying to get through my "thought experiment".
Let's say I have a 480V 60hz 3 phase supply feeding a circuit that comprises of nothing but the conductors themselves (effectively a shorted power supply). Consider the...
Hello again, I have a solution for the question, but as it is my first time solving these types of exercises I am uncertain if I my solution is correct. The first picture represents the exercise with the circuit and the second is the just some rewrites of the circuit, in swedish. Picture 3 and 4...
Summary:: Hi, I tried attempting this problem in alternating current in order to find out the phasors as complex numbers, and I would be more than grateful if someone could peer review it, and confirm my calculations (Please see below both the Figure and the calculations)
Please find attached...
Hi, I am once again asking for help regarding a AC circuit problem. This time I need to compute reactive and active effect for z=R2+C3 in the below circuit. I have already computed u(t) from before so that solves half of the problem. I am unsure if I have done the calculations correct, not much...
I used the voltage of the power supply and resistance to solve for the current in the larger circuit (20V/5ohms=4 amps). I am not sure if the equation listed above is the correct one I should be using, but I tried it using the following numbers. For omega, I used 2*pi*frequency. N should...
My attempt at solving this question:
I realized my attempt is wrong however I just don't know how to proceed in the first step. How can I calculate the phase shift? and find Voltage and Current in phasor form??If I know that, then I can use power factor formula: pf=Pav/V*I
Preface to thread: I am darn well aware of the fact that on an AC circuit, there has to be a line 2 after the load to bring current back to the power source. This thread is about WHY does there have to be a line 2 after the load to bring current back to the power source. I hope that I don't...
Hi all,
Kirchhoff's equation for this simple circuit is equivalent to
\dot I=\frac{V}{L}
Where V=V_0 \sin(\omega t). Integrating both sides should give
I(t) = -\frac{V_0}{L\omega} \cos(\omega t)+c
where c is an arbitrary constant (current).
Here, most of the derivations I've found simply drop...
By combining the formula for the reactance of a capacitor with Ohm's Law for a capacitor, I can solve for angular frequency, and divide by 2π to find frequency.
The resulting equation is:
f = I/(2π VC)
Using the given values, I end up with 5.2 kHz, instead of the correct answer of 5.2 MHz. I...
This may be a stupid question, but here is what I am asking.
Using a very simple circuit, say 120v AC water heating element rated at 1000 watts
meaning 120v AC hot leg on 1 terminal and a neutral on the other terminal.
That would give 8.3 amps of current, meaning the resistance would be 14.4...
The plot of part b is attached below.
I got a warning on part a , I don't know where is my mistake .
Please check my work .
Part A
clc;
clear all;
%parta
f=800;
t=0:10e-6:0.005;
xc=10^(-6);
xl=40e-3;
for i=1:(0.005)/(10e-6)
w=2*f*pi;
zeq=xl*j*w+50;
is(i)=2*(1600*t(i)*pi)...
Hello, I am trying to think of a way to introduce a phase shift in an ac circuit. For example, sin(omega*t+theta) to change theta. How can I go about doing this? I do not think introducing a cap or inductor would work, even though it shifts the voltage from the current graphs (phasors). A...
Homework Statement
Hi I have this question as part of my assignment but cannot get my head around part b, I have worked out part a with an answer of -9.2+17.3i amps which from a previous thread I know is correct, but can't understand why the equations given in the previous thread are different...
Homework Statement
In the circuit diagram shown , Xc = 100 ohm , XL = 200 ohm , R = 100 ohm , the effective current through the source is ?
Homework Equations
Z= √( R^2 + ( XL - Xc)^2)
Vrms = Irms/ ZThe Attempt at a Solution
I tried to draw the phaser diagram and calculate the relation...
The attempt at a solution
(Assuming the components are in series of this order: resistor, inductor, capacitor
So I know that the phases are not in sync, that as the voltage oscillates the voltage across each component in the circuit is different.
At the peak voltage aka peak current the voltage...
Homework Statement
According to Equation 20.7, an ac voltage V is given as a function of time t by V = Vo sin 2ft, where Vo is the peak voltage and f is the frequency (in hertz). For a frequency of 64.7 Hz, what is the smallest value of the time at which the voltage equals one-half of the...
Hi, I have a problem understanding the ac capacitive circuit, where Vc = Vm * sin(ωt), and, current leads the voltage, so at t = 0, v = 0 which means no emf, no pushing energy for the electrons, I think, then how current is max? what is the energy source that supplied the electrons with the...
Hi everyone! This is my first thread :)
I've been working a bit with AC and radio, and would like to make a simple(-ish) circuit in which a 1-volt peak audio signal is stepped up to around 5 volts with a transformer, and is fed into a crystal oscillator to make a crude-but-effective AM...
Homework Statement
2. The attempt at a solution
Am I doing something wrong? I know it's just voltage division with AC phasors and we have to equate the real parts and imaginary parts to find the unknown, but I feel like the question shouldn't be this hard.
Homework Statement
For AC Circuit shown in the picture, ##C=60nF##, ##L=100uH##, ##X_3=-100Ω##, ##Z_2=50Ω## and ##Φ_2=\frac {\pi}{6}##. When the switch is closed the ammeter shows a current ##I_1=0.6A## and the voltmeter shows ##U_l=60V##. The measuring instruments mentioned are ideal...
Homework Statement
More than one options may be correct .
Homework Equations
Inductive reactance =ωL
Capacitive reactance = 1/ωC
The Attempt at a Solution
On increasing the frequency , inductive reactance increases whereas capacitive reactance decreases . Thus , option a) is correct ...
I am retired from a major railroad co. where I worked on electronic weighing equipment. I have an associate of applied science degree from a local university. I have a basic understanding of dc and ac electricity but the explanation I recently read on this forum was the easiest to understand...
This question is from my physics book and neither I nor my teacher can find the mistake in my method. (The original question is not in English so I'll do my best translating it)
> When a coffee maker is connected to the wall (230 V, 50 Hz) its power consumption is 180 W. The power consumption...
Homework Statement
For the circuit given in FIGURE 1 the power factor is 0.72 lagging and the power dissipated is 375 W.
Determine the:
(i) apparent power(ii) reactive power
(iii) the magnitude of the current flowing in the circuit(iv) the value of the impedance Z and state whether...
Homework Statement
An A.C. voltage, V, comprises a fundamental voltage of 100V rms at a frequency of 120 Hz, a 3rd harmonic which is 20% of the fundamental, a 5th harmonic which is 10% of the fundamental and at a phase angle of 1.2 radians lagging.
(i) Write down an expression for the...
I want to calculate Electric field inside and outside a capacitor(two parallel conductor plates and in between a dielectric) which is fed by an AC voltage source. My problem is I do not know how can I relate the electric field to the potential in a capacitor. I got confused about the derivative...
Homework Statement : [/B]
calculate rms value of current i= 3+ 4 sin(ωt+π/3)Homework Equations : [/B]
Irms2=(∫0T [I(t)]2dt)/TThe Attempt at a Solution: I tried to integrate but I'm getting a T term.
Hello!
Recently I was going through some old exams and upon encountering this problem (which seemed pretty easy) I got stuck. Exams at my university are composed of individual tasks, each having three subquestions with four plausible answers respectively. Solution sheet gives results only, so...
【Mod Note: moved from technical forum, so homework template is missing】
In a parallel circuit, one branch contains two equal resistors of resistance ##R_1## connected in series. The other branch contains a resistor of resistance ##R_1## in series with an inductor of variable inductance ##L##...
Homework Statement
the problem is given in the attachment
Homework Equations
basic knowledge of ac circuits and phasor diagrams
The Attempt at a Solution
for point A , i calculated the potential easily. and for point B , i calculated the potential using phasor relationship .. now after doing...
Homework Statement
y = 27
Homework Equations
The Attempt at a Solution
- I calculated the total impedance.
- Divide it with the voltage to get the current.
- Then I use the load impedance to find the voltage load.
- And I calculated the complex power for the load.
I am not comfortable...
Homework Statement
In an undriven RLC-circuit, the characteristic time of the capacitor, ie the time taken for the amplitude of the capacitor voltage ## V_c ## to drop by a factor e, is ## T = 2L/R ##.
We now have a RLC-circuit which is driven by a AC voltage of variable frequency ## \omega ##...
Supposed there is a black box connect to an AC circuit. Inside the black box, there are either a resistor connected with a capacitor or a resistor connected with a inductor. They can be connected either in series or in parallel. The total impedance and phase shift of the black box at 2 different...
Homework Statement
Given the circuit of sinusoidal current (attachment1) with given data:
\underline{Z_3}=200(3-j4)\Omega,\underline{Z_4}=100(3+j20)\Omega,\underline{Z_5}=100(3+j4)\Omega,\underline{Z}=100(2+j5)\Omega,\underline{I_{g2}}=-10(2-j)mA.
After the switch is closed, the increment of...