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Questions tagged [electric-circuits]

An electronic system, with closed loop current flow, and relative electrical potentials present across electrical components.

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1answer
120 views

LC Circuit with a DC input

In the previous LC circuit, if we connect one end with a DC input voltage and the other with ground, what does the oscillating output wave look like? I know that if the capacitor was initially ...
0
votes
1answer
37 views

Resistance and temperature relationship

When the temperature changes from $\theta_1$ to $\theta_2$, having $\alpha$, and the amount of resistance ($R_1$) in the previous temperature ($\theta_1$), we can calculate $R_2$, the amount of ...
0
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1answer
45 views

Calculating electrical resistivity of a material

If I plan to measure the resistivity of a high resistivity material, would it not make sense to alter the geometry of the sensor to make A/l as small as possible and reduce the voltage to get a low ...
0
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2answers
275 views

Current in a RC circuit

In order to find current in an RC circuit, resistance of only the resistor is considered i.e. $I_\text{resistor} = V_\text{resistor} / R$. Why is the reactance of the capacitor not considered? The ...
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0answers
21 views

What is the power dissipated in a conductance in the transmission line? [on hold]

The electric power dissipated due to a resistance is $P=RI^2$. What is the power due to a conductance?
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0answers
18 views

Question about amp-hour and batteries in series

I am a little confused about this wiring batteries in series and parallel and the effect of this on total time that these batteries can last(I suppose this is called amp-hour, correct me if I'm wrong) ...
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1answer
23 views

Combining two power sources to get voltage from one and current from another

For a project, I have to make a battery that output 5 V, 500 mA. However, each one of my cells can only produce 1 V, 80 mA. I can combine these cells in series and parallel to get the required ...
0
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0answers
42 views

Why does current not increase when the voltage increases in this case? [migrated]

When talking about BJT transistors, a very common graph is the one shown below, that plots (VCE,IC) as an ascending function. As far as I know, the BJT manages VCE so that IC is beta times IB, being ...
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2answers
55 views

Why does current always go to the resistance which is lower? [duplicate]

Why does current chose the easy way? Is there a proper mathematical formula about why current tends to go over a resistance which is smaller?
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2answers
45 views

Why does current remain same in a series circuit?

Current is the rate of flow of charges with time. When passing through each resistance in a series circuit, charges lose energy and "slow" down due to collisions with atoms (metal cations). When time ...
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0answers
22 views

Doubt from Transient Circuits [on hold]

(https://i.stack.imgur.com/Rvpl5.jpg) Please solve the question in the image. Can anyone give the general idea of solving such type of problems?
2
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0answers
35 views

Is high frequency alternating current capable of rotating induction motor? [on hold]

I have 100khz AC power that can light up a bulb, can I use this to run small induction motor? I want the Lorentz force to push rotor coil, I know that motor would not rotate at 100000hz rate but it ...
2
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0answers
87 views

Electrical circuit analogue of a nonlinear pendulum

Is it possible to make an electrical circuit analogue of a nonlinear pendulum? To model the equation $$y'' = -\sin(y)$$ They did this on analog computers in the past, but how? How to model the ...
0
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2answers
29 views

Why Does a Bulb’s Individual Resistance Increase When Wired in Parallel?

When I wire three bulbs in a series, the resistance of each bulb is around three ohms (using R=V/I). If I rewire the same bulbs into a parallel circuit, the resistance of each bulb is slightly over ...
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0answers
14 views

Current through the secondary of a transformer

If I know the wattage of the primary of a transformer, and the input voltage, how do I calculate the current flowing through the secondary, if a load of some resistance is placed across the secondary?
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2answers
32 views

What is the reading of a voltmeter if the EMF is 12 V and internal resistance is 3 ohms [on hold]

A battery has emf 12.0 volts and internal resistance 3.00 ohms. A voltmeter is connected to the terminals of the battery; the battery is not connected to any other external circuit elements. What is ...
0
votes
1answer
34 views

Faraday's Law, circuit, current change [on hold]

The answer is A. Why doesn't the current change? The circuit experiences a change in magnetic flux because the area increases. This change in magnetic flux will induce an emf in the circuit. Wouldn't ...
0
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1answer
37 views

How to calculate total power generated?

I have a circuit with a piezoelectric transducer which converts mechanical energy to electrical. The ceramic is connected to a 1 Megaohm resistor and a voltmeter which reads voltage. If I want to ...
3
votes
1answer
47 views

Are Electrons in a Circuit Subject to Newton's Third Law?

Consider a simple electrical circuit made up of a battery, an incandescent bulb, and wire. The battery and bulb are equal in mass and are on opposite sides of a circle made up by the wire. Lastly, the ...
5
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0answers
79 views
+50

Free Electron-Bond Electron Interactions

I am reading an introductory textbook on electronics: Practical Electronics for Inventors by Paul Scherz and Simon Monk. In a section discussing the motion of electrons in circuits, the textbook ...
1
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1answer
59 views

Different batteries in a parallel circuit

I have come across this question in my physics textbook. Two batteries are connected in parallel to a resistor (see the above image). The first battery generates $U1 = 9V$ of voltage and its internal ...
-1
votes
4answers
79 views

What remains the same: voltage, current or resistance? [closed]

A current 1 ampere passed through a conductor which resistance is 10 ohms, if the current become 2 amperes, then will the resistance of the conductor will remain 10 ohms, and if not, then what is the ...
0
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1answer
127 views

Predicting voltages in RLC series circuits from AC source: differences in order?

Hoping this isn't too homework-like, but I'm missing some sort of concept here. Doing a lab, and I have to use previous data to predict the voltage across the 2nd and 3rd elements (e.g. order is LCR, ...
1
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2answers
524 views

Kirchhoff's laws in phasor domain

While analysing AC circuits, we write voltage, current etc all with complex numbers namely "phasors". While studying the same, I wondered if Kirchhoff's laws held good with current and voltage in ...
0
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1answer
20 views

How can be Bode diagram's phase value more than 90 degree or less than -90 degree?

It doesn't have any physical meaning, i think, because phasors doesn't have more than 90 degree or less than 90 degree value ? Also negative resistance doesn't exist.
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0answers
28 views

RMS values and phasor diagrams

In RL circuits (AC source) we use vectors to calculate the total voltage, I understand that we cannot add them algebraically because they do not exist at the same time as we are using rms values for ...
0
votes
1answer
128 views

Negative charge on capacitor, Kirchoff differential equation with step function

I'm solving a differential equation of the form $$200q'+\frac{200}{3}q=3U_o-6U_6+3U_{12}$$ Where $U$ is the Heaviside step function. $q(0)=0 [Coulombs] $ After solving it, I get that at time $t=18$ ...
0
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2answers
28 views

Why do phasor derivations related to LCR circuits consider $V_c = I * X_c$ even if voltage and current are out of phase?

In a capacitor, the current leads by $\pi/2$. But even then derivations of of total voltage in LCR circuits using phasor diagrams assume that $V_{inst.} = I_{inst.} * X_c$ Where $V_{inst.}$ is the ...
1
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1answer
129 views

Assistance with visualization of alternating current

Sorry, I'm already ashamed to ask for your help. But I'm feel that I needed in some hints about how to imagine alternating current. I really realize I have trouble with it during reading this document ...
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0answers
27 views

Resistance of Square + Diagonal [duplicate]

How do you find the equivalent resistance from the top right corner to the bottom left corner, assuming all resistances are different?
0
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3answers
51 views

Voltages phasors in AC circuit

What does it actually mean to add voltages vectorially not algebraically in RL or RC circuits (AC source)? I know that the voltage drop across the inductor is maximum when the voltage drop through the ...
1
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3answers
75 views

RC circuit discharge while being connected to a battery?

I am facing a conceptual problem in analyzing the following situation which was part of a physics exam; A series RC circuit with $R = 200k \Omega$ and $C = 10 \mu F$ is connected to a 5V battery and ...
0
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1answer
131 views

Output in a half wave rectifier

In a half wave rectifier only a single diode is present. One end of the secondary wire of the transformer is connected to the p side of diode while the other to the load resistor. The n side is ...
0
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0answers
27 views

How does a power amplifier works? Does it change the shape of the output signal? [migrated]

I was doing some experiments and I had to put in input a 2V sinusoidal signal at 20Hz through a power amplifier and I got in output an overloaded square signal at +15/-15V at 20Hz. Is it normal? I ...
10
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8answers
1k views

Does Ohm's law $V = IR$ mean voltage causes current, or does it just say that voltage and current are related?

I have read that Ohm's law, $V=IR ,$ just means that $V$ is equivalent to $IR ,$ not that voltage is the cause of current. This is similar to the interpretation of Newton's second law, $\mathbf{F} = ...
28
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10answers
6k views

Is every open circuit a capacitor?

I think that even open-ended wires can let AC current flow through them, just with a low capacitance. I also think an antenna could be a capacitor and open ended. Am I thinking correctly?
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1answer
42 views

Inductors in AC circuits

Although I checked similar questions I still can't understand why the voltage across an inductor connected to an AC source is equal to $L\, dI/dt$ without the negative sign of Lenz's law, why isn't ...
0
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2answers
72 views

Energy dissipated across a resistor when charging a capacitor

I am a beginner in Physics and I am a little confused about RC circuits. I am working on a project in which I am measuring the power loss from a resistor when charging a capacitor in an R-C circuit. ...
0
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3answers
36 views

Flow of charges inside a battery

I am having confusion about the flow of charges inside a battery which is connected to Circuit. Question is, do charges move from one end to another through the battery? If yes, how? Do they move ...
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2answers
39 views

What happens when a battery is dead?

While studying circuits I am having a question that when we say a battery is dead.Do we mean that the voltage difference between the ends has become zero?If no,then what actually happens?
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0answers
41 views

What's the reason for this symmetry argument? [migrated]

Okay so I've learnt about various methods to find equivalent resistance in circuit. But there's one particular argument which I don't understand and I would be grateful if someone will prove it using ...
0
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1answer
20 views

Electric fields and electric potentials in semiconductors

The zener diode is heavilier doped than a normal diode , that is why its depletion region is smaller than the delpetion region of a normal diode and that is why the electric field is very strong.Zener ...
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0answers
17 views

Human vs. machine energy expenditures

I've read that a typical human-powered bicycle power generator generates around 100W. For the same amount of effort, the bike travels probably around 20k/h on a road. Does that mean it requires 100Wh ...
4
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5answers
1k views

Why does not a battery kept in empty space discharge on its own? If space between the terminals is empty, what prevents the electrons to flow?

Given here is the picture of a twisted battery kept in free space (vacuum). Will the battery discharge quickly? I mean, it should discharge faster than it would if we were to connect the terminals ...
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0answers
24 views

Thermistor IV characterisitc

The circuit is a potential divider circuit with a NTC thermistor and fixed resistor. I know generally the IV characteristic for the thermistor however, I was given values of resistors voltage at given ...
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3answers
64 views

Practical usage of batteries connected in parallel

Is there any practical usage in real devices for connecting batteries in parallel? Or is it more a theoretical construct? It seems to me that only batteries in series are used nowdays.
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3answers
64 views

Can anyone tell me why the answer to this question is D? [closed]

I think the current will go through earth wire but my physics teacher told us the current will continue to flow through the circuit.
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2answers
35 views

Adding a capacitor in parallel improves power factor of an inductive circuit?

I know that to reduce power loss during transmission, we require a power factor as close to one as possible. This can be done by making $Z$ tend to $R$ which can be done by increasing $X_c$ such that ...
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0answers
14 views

Zener diode electric field working principle

Well I recently saw a video from khan academy about zener diodes.This video was suggested by another member of Stack Exchange Physics who I thank him very much . But I didnt understand some things:...
0
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2answers
31 views

Empty and fresh battery in series

If you have 2 (e.g. 1.5V) batteries in series and one is dead/empty, what is the reason why a device is not working? Lack of voltage (1.5 + 0 is simply not enough for the device to operate)? From my ...