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

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1answer
630 views

Solving a circuit with Kirchoff/Ohms Law

Good evening, I haven't had physics since year 7 and now I need to use elementary things in university. Since I lack a lot of basics I am now trying my best to fill these holes. Currently I am stuck ...
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2answers
121 views

If connecting an ammeter in parallel will cause short circuit, why won't connecting it in series does?

short circuit will happen when there is nearly no resistance in a wire, and when a high current almost infinite flowing through the wire, causing high temperature. But connected in series, an ...
2
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5answers
4k views

Difference between live and neutral wires

In domestic electrical circuits, there are 3 wires - live, earth and neutral. What is the difference between the live and neutral wires? As there is AC supply, it means that there are no fixed ...
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2answers
48 views

Can someone explain me these doubts regarding voltage in an intuitive way?

This is something I have been thinking for a while. At my level, I don't know much about electric fields. Now, I will be asking two questions: One for series circuit, and the other for parallel. ...
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2answers
78 views

Resistances connected in series

When resistances connected in series then why through each resistances the different potential difference occurs?
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4answers
3k views

Is a capacitor in an open circuit charged?

Say I have a circuit consisting of a battery, a wire, an open switch, and a capacitor. The circuit is open since the switch is open. My book says that the capacitor will only be charged when the ...
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3answers
477 views

How can a voltage across a capacitor be greater than the total voltage applied to the circuit?

I was reading about complex impedance and AC circuits, and I just came across a sentence on a website stating that the voltage across a capacitor can be greater than the applied voltage. How can this ...
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3answers
58 views

Why do we say that there is a voltage drop only when charge passes through a resistor? [closed]

This is a little confusing for me. I will just ask a few questions: First: Am I correct in saying that while traversing through the circuit, charge looses some electric potential(not energy) at ...
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0answers
54 views

Alternating current. Resultant force

I've just been wondering: In an alternating current, the direction of the current is constantly changing. This implies that the acceleration of the charge carriers is constantly changing (pos. neg. ...
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1answer
60 views

Why do we prefer using materials of high resistivity in laboratory instruments?

I know that :$$R=\rho\frac{l}{A}$$ where $R$ is the resistance of the wire, $\rho$ is its specific resistance (resistivity), $l$ is its length, and $A$ is the area of cross-section of the wire. Why ...
0
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1answer
46 views

Short circuit in superposition

I'm really confused about the concept of short circuits. I don't understand, why when you short those two voltage sources, 20 and 10 ohm resistors become parallel? What happens with 4, 12, 15 ohm ...
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1answer
33 views

Using superposition to find current

I'm given the following problem I'm a little bit confused about superposition problems when current flows through a voltage source but not the resistor. 1) When I looked at the solution for this ...
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3answers
11k views

Why connect cells in parallel?

Say there is a circuit with two 1.5V cells, and a 100 ohm resistor. If you connect two cells in series, then the total emf is 3V. And the current will be 3/100 = 0.03 A. (Using V = IR): If you have ...
2
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1answer
53 views

Equivalency of $Q$ Factor Definitions

The Q factor is defined (seemingly) as $$Q=2\pi\frac{\mathrm{energy \, \, stored}}{\mathrm{energy \, \,dissipated \, \, per \, \, cycle}}$$ however on Wikipedia is says that the Q factor can be ...
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0answers
33 views

Why is the force from an electric resistor linearly proportional to the drift velocity?

In a circuit, the potential difference across a resistor is given by Ohm's Law as V=IR. Since the potential difference is the loss of potential energy per charge and the force is -dU/dx, we get that ...
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3answers
65 views

If current is same, is it correct to say that the speed of charge passing through a resistor is more than that of a normal wire?

It took me a long time to understand that current is constant throughout the circuit. And now I am stuck at one last thing: The speed of charge. Here is what I am thinking: Current is defined as ...
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2answers
34 views

Voltage across a resistors

When i was doing the practice problems, I found the following problem: I was able to solve for everything except for V4. When I looked at the solution manual,solution was as follows: Use KVL: V4 = ...
3
votes
1answer
70 views

How does the energy remain conserved in a transformer?

The induced voltage in the secondary coil of a transformer is given as $\frac { { N }_{ S } }{ { N }_{ P } } *{ V }_{ P }$ (where ${ N }_{ P}$ and ${ N }_{ S }$ are the number of turns in the primary ...
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0answers
76 views

Why does a battery die more quickly when more resistors are added to the circuit?

I will be explaining what I think: A battery acts like a pump which provides energy to do work on negative charges to move them towards the negative terminal, and hence creating an electric field. ...
0
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2answers
52 views

Solving for node voltages

I have the following circuit and i need to solve Is, v1 and v2. First of all, I assumed that this problem will involve supernode principle since there is a voltage source between V1 and V2. Then, i ...
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3answers
4k views

Is voltage important when creating a magnetic field?

Would a DC circuit that has a high current and low voltage have a powerful magnetic field? I'm trying to create a powerful solenoid. In order to create a powerful magnetic field, I'm focusing more on ...
3
votes
1answer
37 views

Does the internal resistance of a battery dissipate heat as expected?

A common real battery is often modelled (to a good approximation) as a perfect voltage source having emf $\varepsilon$ with a series internal resistance $r$. So, when a current $I$ is drained from it, ...
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1answer
34 views

Thevenin equivalent voltage and resistance of a circuit: verification needed

Here is my reasoning: We have to sources so me must use superposition: We first replace the current source by its resistance which is infinite for an ideal current source. Now we need to ...
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3answers
89 views

Definition of equivalent capacitance

I know that equivalent capacitance of multiple capacitors in series is $$ C = \left(\frac{1}{C_1} + \cdots + \frac{1}{C_n}\right)^{-1} $$ and in parallel is $$ C = C_1 + \cdots + C_n. $$ But there are ...
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3answers
69 views

Finding the equivalent resistance

I'm having hard times understanding why when you combine 20 and 30 resistances which are in parallel, and then combine 60 and 40 (which are also in parallel) ohms resistances you will get two ...
0
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1answer
69 views

How is a variable potential divider able to reduce current/voltage through a component to zero, unlike a variable resistor?

For example, the diagram in my text book shows a filament lamp, in series with a uniform resistive wire, which can have its voltage and current varied by moving the sliding contact, e.g., a ...
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1answer
67 views

Circuit with three capacitors

A potential difference of V = 38.0 V is applied across a circuit with capacitances C1 = 4.1 nF, C2 = 4.7 nF, and C3= 2.3 nF, as shown in the figure. What is the magnitude and sign of q3l, the ...
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1answer
44 views

Why is resistance $U/I$ rather than $I/U$?

What is the difference between resistance and conductance and why is resistance $U/I$ and not $I/U$? (I know $I/U$ is conductance.) But I don't see the difference between both.
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2answers
40 views

Why do we consider current to be constant throughout a circuit? [duplicate]

Let us consider a circuit made up of connecting wires, a resistor, a switch and a battery. Now, the resistance of the resistor is much higher than that of the wire. Now, intuitively, I am thinking ...
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4answers
147 views

The sign of the current flowing in a circuit

I was doing the following problem: And I was asked to find Iy. I found Iy to be 2.64 using KCL. However, the right answer was negative 2.64. Is it negative only because there is a dependant ...
0
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1answer
34 views

Why does a variable potential divider have the ability to reduce current through a component to zero

For example, the diagram in my text book: shows a filament lamp, in series with a uniform resistive wire, which can have its voltage and current varied by moving the sliding contact, e.g., a ...
0
votes
1answer
61 views

How is a potential divider able to reduce current to zero?

For example, a filament lamp, in series with a uniform resistive wire, can have its voltage varied by moving the sliding contact, e.g., a rotatable wheel. However, why is a potential divider able to ...
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1answer
57 views

Capacitors and external electric fields

I am grading questions from the lab manual provided by the professor to review with the students. I am trying to wrap my head around one of the questions about what an external electric field would ...
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2answers
57 views

What exactly is potential difference? What are the factors that effect it?

I am asking this question because at first I thought that this concept was pretty clear to me, but it is not. So, my first question: Is potential difference only a property of an electric field? If ...
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0answers
14 views

Are diodes (or FETs) electrets?

The explanations I see of diodes and FETs seem to involve various depletion regions, migration of electrons and holes, and the such. My (perhaps naive) interpretation of these explanations implies ...
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2answers
64 views

The separation between the two plates of a capacitor is increased

I had the following question on a quiz recently: A capacitor consisting of two parallel plates, separated by a distance $d$, is connected to a battery of EMF ε. What happens if the separation is ...
0
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1answer
44 views

$P=V^2/R$ confusion

I am confused on how to apply the formula $P=\frac{V^2}{R}$ If I am given a bulb say with power 60W and it is connected to a supply of 120V. Then the resistance of the bulb is 240$\Omega$ but if ...
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1answer
43 views

Why is Kirchoff's Voltage Rule not satisfied when the circuit is shorted?

For example if I have a simple circuit with a battery and a resistor, and then the resistor is shorted, Kirchoff's Rule is no longer satisfied. Since the current through the resistor is 0, the voltage ...
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votes
2answers
85 views

Why didn't 0.2A at 2V kill me? [closed]

I was recently connecting a circuit together like here: and I had the voltage set at 2V, with a 10Ω resistor. By Ohm's law, there was a current of 0.2A (and was confirmed by my multimeter). I ...
2
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4answers
6k views

Capacitor Charging and Discharging when connected to the ground

When we charge a capacitor using a battery and then remove the battery, the plates of capacitor becomes charged. One holds positive charge and the other one gets equal negative charge. o. k. ? Now ...
0
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2answers
60 views

How to find the current source Is and the voltage V1 of this circuit schematic? [closed]

I have Vs= 1.5V, R1=1 Ohm, R2 =6 Ohms, I got the equivalent resistance to be 7 Ohms. Then I set equal Req to Vs for 7I=1.5 and got my current source to be 0.214A. Since it is only Vs and Req in the ...
9
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7answers
15k views

What is Electromotive force (EMF)? How is it related to potential difference?

What is Electromotive force (EMF)? How is it related to the potential difference? Is it created by the potential difference in any conductor? Is it a process? Why is it called force? Does writing EMF ...
0
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2answers
47 views

If the electric potential is location dependent, why do charges loose it when passed through a heavy resistor in a circuit?

I really cannot understand this: I know through reading that unlike electric potential energy, which is charge dependent, the electric potential is purely location dependent. For example: If at a ...
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2answers
77 views

If there is a potential difference between the ends of a battery, does it mean that there is always an electric field?

First of all, I am really sorry if this question is wrong. But, I thought that this would be the best place to ask this. Here is what I am thinking: Batteries promote flow of current in a circuit due ...
0
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0answers
18 views

How to think about Ripple and Noise in circuits

Say you have a AC to DC power supply. If you were to hook an oscilloscope up you would see noise occurring. Some of it would appear to have a regular frequency in Khz or Mhz. Would this put off EM ...
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2answers
30 views

Voltage across voltage source in a short circuit

When we short-circuit a voltage source, the current will be very high. The voltage across the wire is 0V. If we apply KVL, also the voltage across the voltage source is 0V. How can it be 0V if we have ...
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2answers
60 views

Ohm's law experiment

I was going through my physics laboratory manual. In the Ohm's Law Experiment, the book states a few precautions without any reasoning. 1.The wire whose resistance has to be determined should ...
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1answer
91 views

Calculation Equivalent Resistance In A Circuit With resistances connected in a circle [closed]

I am having trouble in finding the equivalent resistance between the terminals 'a' and 'b' in the following circuit: Please can anyone explain to me how to solve such problems. Thank You!
3
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1answer
89 views

Why does energy flow between a high voltage transmission line and linemen approaching it on a helicopter?

The video High power line workers shows linemen servicing a live high voltage transmission line. As the helicopter approaches the line, the lineman reaches out with a metallic wand that is ...
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1answer
61 views

Why is a series resistor needed in a simple thermistor experiment? [closed]

I have come across the following simple question, however I can't see any need for a fixed resistor in series. The only possible reason that I can think of is that the resistance of the thermistor ...