Questions tagged [electrical-resistance]

The tag applies to electrical resistance and resistors. DO NOT USE THIS TAG for non-electrical resistance.

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1answer
38 views

Application of Kirchhoff's rule [closed]

I came across a problem, in which I was supposed to find the power through the 10-ohm resistor, the one at the top (I forgot to label it). I applied Kirchhoff's loop rule and found the current flowing ...
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4answers
195 views

Voltage as work in electric field and in Ohm's law

I am struggling to reconcile the definition of voltage as work done moving a unit of electric charge between two points in an electric field and voltage in Ohm's law. In the work definition, ...
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1answer
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How can I derive the general expression for AC bridge balance?

For example in Maxwell's bridge, or any AC circuit bridge, we just balance the impedances like resistances in DC Wheatstone bridge. How can I derive the general expression below? Z1/Z2=Z3/Z4 For ...
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2answers
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Conceptual question about capacitors in DC circuits

After a long time when the circuit above has reached steady state and the capacitor can therefore be treated as an open circuit, the voltage at the node directly above the 20 ohm resistor is found by ...
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1answer
22 views

How many ampere/current can an electric catfish/electric ray have? [closed]

I know that the voltage of an electric catfish is 300-350 volts, and electric ray varies (ranging from 8 to 220 volts), but what is the ampere of current? I keep searching every time and it only gives ...
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33 views

Relationship between resistance and length in nichrome wire [closed]

The following data was obtained during a resistivity experiment.[![https://i.stack.imgur.com/GkKus.png][1]][1] The resistance for L = 10 cm is ~ 0.9 Ω ( called Ro ) but the resistance for L = 20 cm is ...
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Physics- Resistance [closed]

The diameters of electrical wires are given in gauges. Gauge-20 copper wires, which are 2.053 mm in diameter, are often used in household wiring. a. What is the resistance of a 24 m long gauge -20 ...
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Find the frequency range for which sea water is good conductor [closed]

if sea water has conductivity = 4 mho/m and permittivity = 9*10-9/4*3.14 F/m find the frequency range for which sea water is good conductor.
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3answers
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Do resistors heat up with left-over amps?

Apologies in advance if I misunderstand and for my bad explanation. I have heard that resistors heat up when there are left over amps that are not being used. If this is the case, why do most home ...
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Electric Power ($I=V/R$ vs. $I=P/V$) [closed]

I have a homework question that goes: "A power station delivers $750$ kW of power at $12,000$ V to a factory through wires with total resistance $3.0$ Ohms. How much less power is wasted if the ...
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Calculating the values I need to use for a Colpitts oscillator [closed]

How would I determine the values of the resistors, capacitors and transitor for a Colpitts oscillator circuit, which has a resonant frequency of 10kHz?
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Resonant and non-resonant terms in $RLC$ cirquit

I have tried to solve a differentials equations of a RLC circuit. In the the solution I have terms proportional to $e^{iw_0t}$ and $e^{-iw_0t}$, where $w_0= \sqrt{1/LC}$. The author proposes in the ...
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1answer
26 views

Constant current through a conductor is a problem of electrostatics or electrodynamics?

When you connect a constant voltage source across a resistor, there will be a constant current through the wires. Is this a problem of electrostatics or electrodynamics? If it is a problem of ...
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5answers
376 views

Why complex numbers are used in electronics? [duplicate]

The impedance of a capacitor or an inductor is imaginary. How do we know these quantities are imaginary?
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1answer
20 views

What does the resistance of same order means in wheatstone bridge means?

As we know that in order to increase the sensitivity of wheat stone bridge resistance are of same order but here what exactly order means can anyone give me an example of this order?
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3answers
61 views

How is energy really dissipated in an electric circuit?

I've heard that in a circuit, energy is provided to separate components (lamps, motors, etc.) because of the flow of electrons. How is this possible? Since energy cannot be created, where is this ...
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1answer
25 views

Is there voltage drops across series resistors with a parallel resistor system?

I am not looking for calculations, I can do that. Please forgive the drawing, my picture wont upload. However, (R1 and R2) are in series. Likewise, (R3 and R4) are also in series. I could not show the ...
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3answers
34 views

Confusion about cells in parallel

I cant understand why cells in parallel will last longer. Could someone please explain?
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0answers
15 views

Potentiometer comparison of two resistance [closed]

How is the current in both cases in secondary circuit same because we have changed the resistance first it is R then X so current should change.
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0answers
47 views

Find the current in the 23 ohm resistor using Thevenin's theorem [closed]

How should one proceed to find Thevenin's Voltage across the 23 ohm resistor?
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2answers
39 views

Current in a potential divider [closed]

I dont understand why the current in R wont be the same as that in the 50 ohms resistor. Isnt that the rule for series circuits? The emf for the battery is 18 volts.
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0answers
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How to calculate the battery drain from a LED light knowing it uses 1.5 Ah/month?

My knowledge of physics is basically zero, so I hope this question can be considered on-topic! This thingy connects to the battery of a vehicle (car, motorcycle, scooter etc) and shows the level of ...
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2answers
43 views

Why is the resistance in a coaxial cable inversely proportional to the length?

I have two coaxial metal cylinders of radii $a$ and $b$, respectively, separated by some conducting material. I have the relevant expression for the resistance between the two cylinders; however, it ...
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1answer
39 views

What is the microscopic explanation for why is there more power in a circuit with a smaller resistance?

According to the Drude Model of electron flow in a circuit, the drift velocity is inversely proportional to the resistivity. $$E=\rho J$$ $$E=\rho Nev_d$$ $$E=\frac{-\rho Ne^2E}{m}\tau $$ $$\rho=\...
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4answers
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Where does energy go in joining capacitors of different capacitance charged by different potential, hypothetically assuming no resistance in circuits?

I don't understand why there is any change in initial and final energy since we have already assumed a perfectly conductive circuit. I mean, theoretically at least, there should be no change in energy....
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4answers
134 views

Do electrons deccelerate through a resistor?

In a circle the voltage drops across a resistor. This means that some electrons lost some of their electrostatic potential energy. Where does that energy go, and how? For potential energy to be lost ...
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1answer
64 views

Relation between $V = RI$ and Ohm's law

According to the book Halliday et al., the equation$V = RI$ is not the Ohm's law but simply the resistance definition; the book states this definition applies to all kinds of conductors, ohmic or not. ...
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17 views

Large Equivalent series resistance for polarized capacitor

Consider a standard RC circuit with a $100 k\Omega$ resistor and a capacitor. Here's some issue encountered during the lab. When using specifically a polarized capacitor($20 \mu F$), in addition of ...
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1answer
35 views

Energy stored in a capacitor vs Work that the battery does [duplicate]

Say we have a battery at a fixed voltage of $V$ charging a capacitor with capacitance $C$. When the capacitor is fully charged, the energy stored in it will be $\frac{1}{2}QV$, where $V$ is the final ...
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5 views

What is the maximum negative output voltage of an emitter follower with a split +10v/-10v supply? [migrated]

I'm perplexed by a passage in Horowitz and Hill's "Art of Electronics" (1st ed., p. 54). They present the reader with a simple emitter follower circuit. The input voltage is a 10v amplitude sine-...
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2answers
124 views

Do metals at low temperature follow Ohm's law?

I think metals at low temperature do not follow Ohm's because of superconductivity. Is it true? What about metals at high temperature?
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1answer
39 views

In a simple circuit with only cell and wire, where is the electrical energy lost (what causes potential difference)?

Imagine a simple cell circuit with a nine volts cell. Because of the cell, there is a potential difference of 9V between 2 points on the circuit. Because $$Energy at a point = charge * electric ...
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2answers
62 views

RC time constant in parallel circuit [closed]

$R_1 = 50k \Omega $ $ R_2 = 100k \Omega $ $ \mathcal{E} = 10V $ $ C = 10 \mu F $ So I want to find the $\tau$ time constant of this circuit after the switch is closed. The only issue is that ...
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2answers
44 views

Why do charges not lose potential as they travel through the circuit before reaching a resistor? [duplicate]

Voltage is defined as: Given the circuit: Why would potential not drop, from the point differentially away from the positive terminal on the battery, to the point I have labeled. I understand that ...
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0answers
13 views

How to decease conductivity of $\rm SiC$?

green SiC is n-type semiconductor with the resistivity of 10to3 10to 5. I need to increase resistivity of sintered SiC ceramics. One way of doing it is to add some impurities that will act as a deep ...
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1answer
26 views

RLC Bandpass Filter network

Can anybody tell me what the "s" in this equation is? I am looking for the transfer function of this circuit
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8answers
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Clarification of the concept “less resistance means less heating” in a wire

So my textbook says that the reason cables that are suppose to carry high currents, are thicker that those that are meant to carry lesser current, is that "less resistance (of the wire) means less ...
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2answers
35 views

Resistance in special cases

I am curious- I know that resistance doubles when length does, and that resistance would be halved if cross sectional area was doubled - But is there such a case of special conditions where It ...
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1answer
17 views

Time constant relevance and definition for an RC or any 1st order RC/RL or a 2nd order RLC circuit

Can someone clearly explain what it is meant by the time constant of an RC circuit. Because from what I have been told it is the time taken to charge the capacitor. However, when I search on google it ...
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3answers
156 views

Simple Kirchoff's Law Problem [closed]

I'm stuck on a fairly simple problem regarding Kirchoff's law, using this diagram: The question asks: What is the current through the $10.0$ V battery? The solution manual says that the answer ...
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1answer
36 views

Why does the galvanometer read 0 at a certain point?

We are studying potentiometers in class, and our teacher wasn't able to explain why the galvanometer would read 0 at a certain point along the wire. I think I'm not quite understanding how the current ...
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0answers
27 views

How to find the potential difference in a circuit with internal resistance

So I want to find the potential difference between points $a$ and $b$. I'd first need to find the total current in the top and bottom loop (middle one doesn't participate in the circuit). I can do ...
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1answer
31 views

Why do we leave out this 20 ohm resistor when tabulating the Thevenin resistance? Is it because of short circuit? [closed]

I bumped into this particular question. I approached the question in the wrong way. I took into consideration of the extra 20 ohm resistor. but the answer key doesn't seem to consider that. Is it ...
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1answer
35 views

Why is the EMF=terminal voltage in an open circuit

Now a trivial answer would be that the current is 0. V= E-Ir (where v is terminal voltage, e is emf, I is current, and r is internal resistance) Since i=0, V=E But one thing I believe we are ...
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1answer
54 views

How same power is distributed in different voltages in power lines?

I have seen when a resistor is connected to a battery, it carries the same voltage across the resistor, if the resistance is changed the current changes but voltage remains the same making the battery ...
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3answers
56 views

What does an incompleted variable resistor mean physically?

In the diagram below, the resistor has three terminals I believe. Now in this circuit, my book tells me, that only two terminals are being used (to alter the resistance by sliding the metal contact). ...
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2answers
82 views

How is this a parallel circuit?

I understand that here, the current has a choice to flow through one resistor and back to the terminal WITHOUT going through the other. Is this, a parallel circuit? I don't get it. Sorry if this is ...
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0answers
23 views

Why does an oven burn out when all knobs are on? [closed]

I'm having serious trouble understanding this. If a fuse burns out when too much current is flowing through it, then how does turning on all knobs to their full setting burn out the wall-plug? ...
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0answers
42 views

In an $RC$ Circuit, when polarity of a battery is reversed, how much energy is dissipated into heat?

https://ibb.co/tPL02dZ In the figure, a $ 20 nF $ capacitor is connected in parallel across a $ 30 nF $ capacitor. There are $2 $ resistors of $10 Ω$ connected in series with the capacitors. A ...

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