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

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138 views

Power loss and Joule's law of heating

I really can't understand the power loss law. If we have a wire carrying a $15\:\mathrm{V}$ and $1\:\mathrm{ A}$ going into an inverter, giving $150\:\mathrm{V}$ and $0.1\:\mathrm{A}$, if we want to ...
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0answers
33 views

Help with inductance and a moving (rolling) rail problem

I can't even do the first part. I've exhausted just about every direction. I've done plenty of moving rail problems without rolling, but I'm guessing you have to have some relationship between the ...
5
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3answers
6k views

What happens when we connect a metal wire between the 2 poles of a battery?

As I remembered, at the 2 poles of a battery, positive or negative electric charges are gathered. So there'll be electric field existing within the battery. This filed is neutralized by the chemical ...
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2answers
451 views

Measuring human resistance with a DMM

When I attach a Digital Multimeter (DMM) to read the resistance between my right and left hands, the resistance starts off high and reduces over time. It appears almost like "RC-type" behavior. Can ...
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3answers
4k views

What is a virtual ground?

What is a virtual ground? I would like to know what it is.
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2answers
783 views

how does an electric field comes inside a conducting wire inside the circuit? [duplicate]

This has been a really great confusion for me now .... Many places i have read in books that when a potential difference is applied across the ends of a wire a constant electric field is generated ...
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4answers
344 views

How can there be a Current and an Electric field in an idealized wire with no voltage drop?

In an ideal circuit, How can there be a current b/w points a & b, when there is no potential difference and thus no electric field between a & b? If there is no current, then where does ...
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0answers
37 views

Determine the current and voltage for every component in the following circuit [closed]

Determine the current and voltage for every component in the following series circuit What is the voltage and current through R1 and what is the voltage and current through C1? $V_1= 20\,V$ $R_1= ...
2
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1answer
323 views

Graphene batteries/super capacitors

A while ago, there was some news about micro-scale graphene-based supercapacitors and these devices can charge and discharge a hundred to a thousand times faster than standard batteries. Question: ...
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1answer
110 views

Kirchoff's Junction Rule

I understand that the Junction rule states that the algebraic sum of currents going into a junction equals the current going out of the Junction. There is just a wrinkle that I don't understand. If ...
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2answers
111 views

Is there a differential equation that can represent a circuit with an arbitrary voltage source connected acrorss an antenna?

An RLC circuit with a voltage source can be characterized by the differential equation: $$ LC\;\ddot{I}\left(t\right) + RC\; \dot{I}\left(t\right) + I\left(t\right)-C \;\dot{V}\left(t\right) = 0 $$ ...
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1answer
115 views

Magnetic core, and a DC solenoid

A DC solenoid creates a magnetic field B. A highly permeability magnetic core is added to solenoid to increase B. Now, there is change in flux, due to the increase in magnetic field. What would be ...
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2answers
6k views

Different batteries connected in parallel

If we have 2 batteries one of emf x and the other is of emf y and we connect them in series we get an effective emf of x+y. But what if we connect them in parallel, how to calculate the emf now?
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1answer
118 views

Voltmeter Question [closed]

I understand that a voltmeter is used for measuring potential electrical difference, but how exactly should said voltmeter be connected with the resistor in circuit?
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2answers
57 views

Calculating the power of a lightbulb [closed]

How do I calculate the power of a lightbulb? I have values but I don't know the equation to use.
2
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1answer
81 views

Calculate required voltage in mixed circuits [closed]

Q: Calculate the voltage that V1 has to provide Given: The following circuit. The voltage through LAMP1 is 5.0V. A (U,I) chart (not shown). LAMP1 and LAMP2 are identical, non-ohmic lightbulbs. ...
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0answers
403 views

Finding potential difference (PD) between two points [closed]

How do I find the potential difference between two points in a circuit without using Kirchhoff laws?
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1answer
242 views

Hard circuit problem [closed]

I want to find the p.d. between points A and B. I'm not sure how to approach this problem though, could I have a hint?
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1answer
398 views

Zener diodes - how do they work?

I was going through some of the theory behind Zener diodes. I know what they're used to work at constant voltage, but I don't know how they work. Actually, I kind of get that too, I know that voltage ...
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3answers
72 views

Electric Current Power Calculations [closed]

With regards to the equations: $P=VI$ ; $P=V^2/R$ and $P=I^2R$, if you are given $P$, $V$, $I$ and $R$ for a circuit, how do you know which equation to use? Does the use of an equation have to do ...
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1answer
51 views

In what way do passive circuit elements change the functional form of the voltage?

I heard capacitors affect the valleys and mounds of voltage sine curves, so that you get DC from AC. It's related to Graetz bridge, flipping signs of sine waves and seemingly afterwards smoothing ...
3
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1answer
310 views

Sign conventions for voltage drop and gain in circuit

In Sears and Zemansky's University Physics book and in many other books in English they define the following sign conventions (used for Kirchhoff loop rule for example): While in many other books ...
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2answers
85 views

Time difference in transmission of AC and DC

Is there any time difference while considering the transmission of AC and DC ? Is either one of them faster than the other one in terms of transmission of energy/power from one point to another? I ...
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3answers
2k views

Power dissipated in Series versus Parallel

Do two resistors in parallel dissipate more heat per unit time for an applied voltage when compared to two resistors in series?
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1answer
167 views

How to imagine the first few moments of an LR circuit?

For example, there's a very simple circuit which only contains on resistor. So according to Ohm's law, we have: $\mathrm{emf} = IR$ As we know when time $t = 0$, the current must be $I = 0$. However, ...
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1answer
2k views

Does the phase difference between voltage and current in an LCR circuit exist throughout the circuit?

I know that in an purely inductive circuit the current lags behind voltage by $90^o$, in a purely capacitive circuit vice-versa and in an LCR circuit the current may lag or gain with respect to ...
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2answers
58 views

Direct current and metallic conduction

Suppose we have a circuit with and EMF source and a resistor. We know that when electron moves from one terminal of a voltage source to another it encounters resistance, which is basically collisions ...
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1answer
99 views

Resistance and current

I'm not a current student at any school, but I am learning a new profession, and some of it is a basic understanding of elecrticity. I have some knowledge, but definitely not enough, and I have had to ...
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5answers
263 views

Intuitively, Why is Power Proportional to $I^2R$

As the resistance of a circuit goes down, the power increases because the current increases, assuming constant voltage. Why is this? I feel like resistance and current are inversely proportional, so ...
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0answers
82 views

Circuit Analysis: Help getting the Thevenin equivalent [closed]

I am attempting to solve this problem which requires me to get the Thevenin equivalent of a circuit, and I've gotten as far as getting the equivalent resistance of the circuit (which I believe is 5 ...
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1answer
77 views

Electrical circuits problem

Batteries have a circuit which looks like this : The electrons go around the circuit and then return through the battery where they get charged again and flow around. My issue is, what about ...
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1answer
115 views

Find current in a nontrivial circuit

Let us assume that we have this circuit: We know that: $$I_1 = I_2 + I_3$$ $$I_1R_1 + I_3R_3 = V$$ $$I_1R_1 + I_2R_2 + \dfrac{q_c}{C_1} = V$$ Therefore we can write: $$I_1 = k_1 - k_2*q_c$$ ...
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0answers
78 views

How is derived the relation between capacitances when a $Y-\Delta$ transformation is applied in a capacitors network?

A $Y-\Delta$ transformation can be applied to circuits in order to make an equivalent circuit (but simpler to put in terms of series/parallel devices). Wikipedia and other books show how to deduce the ...
2
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5answers
240 views

Current division in ideal inductors?

The Question is:- Find the current distribution in the inductors at steady state (i.e. assuming $t\rightarrow \infty$ after the switch is closed and circuit established and consider the ...
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1answer
77 views

How uncertainties affect values

If I calculate the equivalent resistance of a circuit, for example: $$1/R_{eq} = 1/R_1 + 1/R_2 + 1/R_3 = 1/1472 + 1/3260 + 1/5580 \Rightarrow R_{eq} = 858.22\,\Omega$$ And then calculate its ...
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2answers
87 views

can resistance be found without knowing length?

is it possible to find to resistance without knowing the length? i am tryigng to solve a problem that requires me to find the resistance.I cant seem do so without knowing the length of the circuit ...
1
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1answer
78 views

Resistances in a circular loop

I have no idea what formula I'm supposed to use.I just want to know the concept that would allow me to get the answer. I know basic concepts of electricity like charge, currents, etc., but as far ...
1
vote
1answer
242 views

Why the electric bulb turns on almost instantly when the switch is closed? [duplicate]

The electron drift speed is estimated to be very low.How could there is current almost the instant a circuit is closed?? By the discussions it is known that The information about beginning of the ...
2
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2answers
115 views

Strange electrical circuit

This is a question I would like to have an explanation with: It's in this PDF, question 9. In that circuit, if switch 1 is closed, bulb A burns normally. If 2 is closed as well, do other lamps ...
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2answers
80 views

How long should I leave the light on?

I remember my old physics teacher at school saying that if you switch a light on in a room and you're planning to return relatively quickly, it uses less electricity if you leave the light on until ...
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2answers
403 views

Why is the voltage drop across an ideal wire zero?

I'm having trouble conceptualizing why the voltage drop between two points of an ideal wire (i.e. no resistance) is $0~V$. Using Ohm's Law, the equation is such: $$ V = IR \\ V = I(0~\Omega) \\ V = ...
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3answers
463 views

How does electricity 'decide' on it's pathway? [duplicate]

I'm struggling to understand the fundamental concepts of electricity, more specifically, the way in which it 'chooses' its optimal pathway. I appreciate electricity will always choose the path of ...
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2answers
139 views

Does the heat produced in an inductor affected by the total current in the resistance in the circuit?

The energy stored in an inductor depends on the inductance of the inductor and the current flowing through it. But, assume that the switch is opened. Then, does the heat generated in the inductor ...
0
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1answer
71 views

Simple circuit with resistances

I have a question about a circuit that I made in class! So, we had a circuit with 2 resistors, one of $R_1 = 330 \Omega$ and one of $R_2 = 470 \Omega$. The tension applied to the circuit should be ...
0
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1answer
64 views

Loop Rule Parts Problem

[Loop Rule Diagram] The problem is thus: Apply the loop rule to abcdefghia and find the expression which adds to zero. I tried this, but I was not able to get it correct. I know that when crossing ...
2
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1answer
411 views

Is the standard explanation for the ring launcher incomplete?

Related: Faraday's law in a ring The ring launcher is a standard introductory physics demonstration that I assume almost everyone has seen (if not, YouTube it). The explanation of why the ring is ...
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3answers
2k views

Detecting if resistances are parallel or series in complex circuits

I know how to detect when resistors are arranged in parallel or series arrangement and I can also find their equivalent resistance in simple circuits or when resistances are connected in form of ...
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1answer
137 views

Is this a series or parallel connection?

I am confused how the capacitors in this circuit are connected. $C_4$, $C_6$ and $C_5$, $C_3$ appear to be parallel, but both $C_4$ and $C_6$ seem to be in series with $C_1$ as do $C_5$ and $C_3$. Am ...
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3answers
476 views

Calculate for Multiple Resistors with a Bridge

Background A circuit is constructed with five resistors and a battery as shown. The battery voltage is V = 12 V. The values for the resistors are: R1 = 78 Ω, R2 = 150 Ω, R3 = 132 Ω, and R4 = 83 Ω. ...
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1answer
247 views

$\pi/2$ phase shift in RC circuit

I just recently learnt Alternating Current and RCL circuits and I also learnt about phasers and various graphs. Now I also know that current lags in an LR circuit. My intuitive understanding of this ...