# 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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### 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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### 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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### 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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### 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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### 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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### 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]] 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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### 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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### Are the reference directions of voltage and current associated [closed]

Are the reference directions of voltage and current associated
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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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### 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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### 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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### 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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### 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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### 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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### Confusion about cells in parallel

I cant understand why cells in parallel will last longer. Could someone please explain?
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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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 ...
### 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 ...