0
votes
2answers
20 views

potential difference in parallel connecting resistors

How could the potential difference be constant across all the resistors of parallel connecting resistors although each resistor has a specific resistance?
1
vote
3answers
54 views

How does Ohm's law apply to superconductors?

As radio amateurs we've all learned the various relationships of power, voltage, current and resistance as expressed in Ohm's Law. My question relates to the following simple circuit showing an ideal ...
2
votes
2answers
55 views

Difference between $I^2R$ and $V^2/R$ and $VI$ for measuring power $P$

We use $I^2R$ or $V^2/R$ or $VI$ for measuring power $P$. Are all of these applicable for all circuits? I have seen in some circuit $V^2/R$ is not equal to $I^2R$. Why is that?
0
votes
2answers
26 views

Energy stored in a capacitor in an RC circuit

Suppose we have a capacitor of capacitance $C$ and a cell of emf $E$, why is the maximum energy stored in a capacitor equal to $\tfrac{1}{2}CE^2$? I feel confused because, the potential difference ...
-2
votes
1answer
21 views

Calculate the current in mA which will be flowing through the two resistors [closed]

Three resistors of 3,4 and 5 ohms are joined in parallel in an electric circuit. If a current of 150mA flows through the resistor of 4 ohms,then calculate the values of the current in mA which will be ...
0
votes
1answer
87 views

Why isn't resistance proportional to distance squared

Here we have a wire. At both ends there is an equal and opposite field caused by a chemical reaction. So, if we decrease or increase the distance between the two points, the strength of the field ...
2
votes
0answers
60 views

Q factor of parallel RLC circuit in series with a capacitor and resistor

I know that for parallel RLC circuits, the $Q$ factor is given by: $$ Q = R \sqrt {\frac{L}{C}} $$ But now suppose it is connected in series to a resistor $R_2$ and capacitor $C_2$. Would the $Q$ ...
0
votes
1answer
55 views

Simple Parallel Electric Circuit [closed]

Ammeter (A1) and voltmeter (V) in series have parallel connection to another ammeter (A2). Currents in A1 and A2 are respectively 0.2 and 1.7 amp. Voltmeter's voltage is 6 volts. How should I find ...
0
votes
3answers
76 views

Could this open electric circuit work?

Two batteries are interfaced by a resistor. Parameters such as resistance can be set arbitrarily. Does it work?
1
vote
1answer
73 views

Interpreting Physics Results Regarding Circuitry Analysis (Highschool Level Physics) [closed]

I conducted an experiment which aimed to detail and record the voltage across series resistors in series circuits. I noticed that: The Final Voltage, V3, stayed the same. The resistors with the ...
1
vote
5answers
141 views

Ohm's Law Intuition

When we derive Ohm's Law using the Drude Model, we assume at one point of time that $E=V/L$, when is fact, $E=dV/dL$, unless $E$ is constant, in which case the assumption $E=V/L$ is true. But I don't ...
1
vote
2answers
102 views

Having trouble understanding the concept of current and Ohms law

Circuit in series: $10\,\text{V}$ power supply, 2 resistors connected. Each resistor is $10\,\Omega$, total of $20\,\Omega$ resistance. If I put an ammeter at the end of the circuit, will the current ...
0
votes
1answer
57 views

Ohms law and multiple resistors

In my physics class, we did an experiment in which we supported Ohm's law. We used a simple circuit that includes one resistor. The relationship of I = VR, and variants thereof, became apparent. We ...
1
vote
3answers
55 views

Resistor and LED - together and separated

Something very basic which I don't get no matter how much I read. circuit A: only a resistor and power supply - the resistor will burn. circuit B: only a LED and power supply - the LED will damaged. ...
1
vote
2answers
345 views

Proof of Thevenin and Norton theorem

How can I prove Thevenin's and Norton's theorem? Thévenin's theorem can be used to convert any circuit's sources and impedances to a Thévenin equivalent.
1
vote
1answer
49 views

Do I understand impedance correctly?

$$Let\quad \vec { Z } =R+Xj$$ If $X>0$,then the impedance is lagging (current lags behind voltage).If $X<0$, then the impedance is leading (current leads voltage or more accurately, voltage lags ...
14
votes
4answers
1k views

What's the physical meaning of the imaginary component of impedance?

As you know, impedance is defined as a complex number. Ideal capacitors: $$ \frac {1} {j \omega C} \hspace{0.5 pc} \mathrm{or} \hspace{0.5 pc} \frac {1} {sC} $$ Ideal inductors: $$ j \omega L ...
1
vote
1answer
52 views

Circuits and Power

"The diagram below represents a simple circuit composed of 5 identical light bulbs and 2 flashlight batteries. Which bulb (or bulbs) would you expect to be the brightest? a) V only b) V and W ...
0
votes
1answer
48 views

Ohms Law Voltage/Potential Difference [duplicate]

Three 2.0 Ω resistors are connected in series to a 12 V battery. What is the potential difference across each resistor? � This question requires Ohms law because V is needed right? So I would use I = ...
0
votes
1answer
47 views

Back EMF & Current, how can we make I stable?

Lets assume we have a wire that has $10V$ across and $1$ $Amp$ flowing, now if this conductor is introduced to a changing magnetic field, $-EMF$ is induced, can we control our voltage to increase it ...
0
votes
1answer
51 views

Voltage across parallel combination on adding another resistance

Suppose we have a battery with terminal PD $V$ connected to an external resistor of resistance $R_1$. Now if another resistor say $R_2$ is added in parallel to $R_1$ , does the potential drop across ...
0
votes
3answers
85 views

Weird resistor patterns [closed]

I came up with the following question: The vertices of tetrahedron ABCD are all connected by 1-ohm resistors. What is the total resistance between A and B? I haven't the faintest idea how to ...
0
votes
2answers
51 views

Is this way of solving Thevenin theorem correct?

This thevenin theorem is really giving me a headache, and I've really searched many sources in the internet but they confused me more and more. Take this as an example: The guy in the above link ...
-2
votes
2answers
58 views

Resistances connected in series

When resistances connected in series then why through each resistances the different potential difference occurs?
0
votes
1answer
160 views

The shape of the graph of the equation: $V= -r I + E$

I have recently collected data (for a school experiment) in order to measure the EMF and the internal resistance of a solar cell. The data complied with the equation: $V = -rI + E$, i.e. the voltage ...
1
vote
1answer
98 views

Kirchoff's rules and RC circuits [closed]

You can view the image bigger: http://i.stack.imgur.com/4moUP.png I'm studying RC circuits and I can't understand the part when we use Kirchoff's rule. When working with batteries, when we're ...
1
vote
1answer
64 views

If you have $N$ 1ohm resistors, how many distinct equivalent resistances can you create?

If you have $N$ 1ohm resistors, how many distinct equivalent resistances can you create? Assume that only parallel and series and mixture of them is allowed and no bridging between two parallel ...
1
vote
0answers
171 views

How does a Photocell/Photoresistor work? [closed]

I'm just curious highschooler beginning an interest in electronics and this concept of light detecting resistance component is really intriguing to me. I assume it's an application of the ...
1
vote
5answers
200 views

How does series circuit differ from parallel circuit?

Why does same current $I$ flow in the series circuit but it isn't the case with resistors in parallels?
1
vote
0answers
186 views

Power dissipated through resistor in RC circuit with charged Capacitor [closed]

so here's the problem: A simple RC circuit where the capacitor has been charged, and two resistors are in parallel configuration. How does one find the power (as function of time) through any of the ...
2
votes
1answer
91 views

Do batteries lose charge?

Say I have a charge of +q and -q on the positive and negative terminals of a battery. If I connect wires to each terminal, but don't connect the wires (essentially creating an open circuit), the ...
0
votes
1answer
82 views

Changing the resistance of a circuit

I am wondering, when we change the resistance in a circuit, does the voltage tend to increase or the ampere decrease? More specifically, under what conditions does what happen? E.g. If we have a ...
0
votes
0answers
27 views

Quadrupling Power in a Circuit

If I have a heating wire with resistance $R$ to be connected across a constant potential difference $V$, it would seem like cutting the wire into two (thus each having half the resistance) and ...
2
votes
1answer
237 views

How do capacitors work?

Say you have a battery, with a wire connecting the negative and positive terminal. Initially, (the transient state) the electric field is not uniform and is perpendicular to the surface of the cross ...
0
votes
1answer
267 views

How to find power factor value of parallel RL circuit knowing the power factor value for the series circuit with the same components

Because I know the value for the power factor for the series RL circuit I've tried to find the ratio between the series circuit power factor and the parallel circuit power factor, expressed in terms ...
0
votes
0answers
17 views

Resistor connections [duplicate]

I can't figure out what kind of connection it would be if i put resistors like this Can someone please explain how they are connected, like is R1 and R2 in series and R4 and R5 in series and then I ...
0
votes
0answers
63 views

Need to find the Vab of this circuit! [closed]

Find Vab in the circuit http://imgur.com/IqZ7Yis I uploaded a picture of the circuit. I tried adding 10 and 5 (top) because they appear to be in series. I also added 10 and 15 (bottom two) because ...
-1
votes
2answers
80 views

How to convert RL Circuits? [closed]

How do we convert a parallel RL circuit into its equivalent series RL circuit ?
3
votes
1answer
624 views

Delta to Star/Y Conversions and vice versa in Electric Ciruits

We all know the basic rules for conversion of $"Delta"$ circuits to $"Star"$ circuits and vice versa. We also know that this is needed for simplification of circuits in complex cases. Can anyone ...
1
vote
3answers
1k views

Unbalanced wheatstone bridge

Suppose I have an unbalanced Wheatstone bridge (resistances $R_1, R_2, R_3, R_4, R_g$), to which I apply some voltage $V$. I need to find the voltage across the the galvanometer. Solving the system of ...
1
vote
1answer
146 views

Traditional Kirchoff voltage law in AC circuit?

The traditional (not taking into account phasor addition or complex addition) application of Kirchoff Voltage law, i.e. $\Sigma\Delta V=0$ along a loop, does not work for AC circuits. We can sum the ...
2
votes
0answers
75 views

The origin of contact noise?

I was trying to measure the noise of a device with metal probes. I was not sure whether I should trust the results because I was told contact noise might contribute to some degree. I am a little ...
0
votes
3answers
353 views

Resistors in series vs parallel

I understand that for resistors in series we need to add R for each resistor to get the equivalent resistance, where R is resistance. I also understand the mathematical manipulations that show that ...
2
votes
2answers
922 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 ...
3
votes
4answers
509 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 ...
-2
votes
1answer
336 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?
-1
votes
3answers
84 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 ...
1
vote
1answer
126 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 ...
1
vote
0answers
91 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 ...
4
votes
5answers
399 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 ...