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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Why do we need to have a low voltage drop over long distances in transmission of electricity? [closed]
It is said that AC is preferred over DC because of the negligible voltage drop over long distances. How does that work?
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Overdamped RLC circuit
I have a series RLC circuit with an equation:
$$\frac{d^2I}{dt} + 2\alpha \frac{dI}{dt} + \omega_0^2 I = 0$$
(No outside sources affecting the circuit, only some $I_0$ was in the circuit at the ...
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Circuit Diagram Problem [closed]
I solved a problem in which I was supposed to find the current over the ammeter. The answer is 12 because the total voltage over the circuit is given as 128 V. However, I do not understand why we don'...
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What are Cooper pairs in superconductivity? [duplicate]
At low temperature how does electron become Cooper pair and why can they pass through a superconductor without resistance?
Please give quantum mechanical explaination.
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What exactly is "voltage drop" across a circuit element?
what exactly is "voltage drop" across a circuit element? I don't quite understand what this means.
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As there is a potential drop across resistance, then why in parallel circuits the voltage across resistances is same as that of battery?
In textbooks it’s taught that in parallel circuits the voltage across resistances is same as that of battery but after that we also read the concept of potential drop across resistances, which creates ...
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Infinite triangular Resistance [closed]
A classic problem but I couldn't find the answer I want.
Determine the resistance between the points A and B of the frame made of thin homogeneous wire (as shown in figure), assuming that the number ...
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Electrical circuits and calculating resistance [closed]
Can anyone give me some ideas about how to simplify this circuit....
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How to determine direction of the current in the following circuit? [closed]
What would be the direction of the current on R3? Can there be current moving in both directions?(left and right?)
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Charge distribution in the wires and resistor, in a DC circuit
1) How do the electrons in a wire with 0 or negligible resistance arrange themselves in order to make the field in the wire 0?
2) The electric potential drop across a resistor is far more than ...
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Why does the full PD across a battery manifest itself across a break in a circuit at any point?
Consider the following circuit:
I want to know why the full pd of the battery can be measured across the break if a voltmeter was connected. Surely when the whole circuit was closed the charges at ...
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How do charges lose electrical potential energy when going through a resistor?
I can understand that the charges need to do work against the resistance - which transfers energy to forms such as light, heat, etcetera - using the electrostatic force provided by the battery ...
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Electric Potential drop in wires
Electric potential is related to Electric Field by negative integral of Field with distance.If charges move away from the positive terminal (Assuming conventional flow) why is there no drop in ...
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Simple electronic circuit analysis [closed]
I have to find a substitute for this circuit. (The substitution is on the right)
The arrows in one circle are perfect voltage sources.
The arrows in two circles are perfect current sources.
It ...
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Do superconducter wires still have low resistance above their transition temperature?
Superconducting wires have almost zero resistance below their transistion temperature. But do they still have resistance better than other wires above that temperature?
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Why do we use the RMS but not the fourth root mean quad?
Why do we use the power of $2$? What is the relation between this and having the same heat energy in both AC and DC?
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Kirchoff's Second Law [closed]
I am failing to get a proper intuition on Kirchoff's law. If any closed loop has sum of pd and emf equal to 0, does that mean that this picture's loop also follows the same? I am not able to draw a ...
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How could a bulb light up if aĺl the voltage is lost in the resistor?
I recently came up with this slight confusion about voltage loss in resistors/resistance. So for example My circuit has a 12V battery, a 2 Ohms resistor and a Bulb. If we use the V=I.R formula then a ...
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How does the internal resistance of a cell vary with temperature?
Does anyone have a physics explanation to why the internal resistance of a battery decreases as the temperature increases?
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What is the difference between a galvanometer, an ammeter and a voltmeter?
I'm looking for basic differences b/w the three with respect to nature of the circuit as well i.e either it is connected in parallel or series, and also the reason as to why they're connected the way ...
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Why doesn't using more appliances at home decrease the electricity bill? [closed]
I know that at home the electric circuits are parallel, and this explains why if one appliance (eg bulb) fails, everything else continues to work, but if more devices are added in parallel to each ...
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circuit analysis [closed]
I have been struggling with this circuit below since my teacher asked a question about it.
The question is:
-Is there any current flowing in the wire in
the middle?
The answer is yes.
I tried to ...
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What does it mean if the resistance of a semiconductor increases due to light?
I have synthesized an $n$-type semiconductor material $\text{ZnO}$. Under light illumination, its resistance keeps increasing. What are the reasons for this?
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Reconciling two views of Matthiessen's rule for electron mobility
My understanding of Matthiessen's rule is that when electron conduction in a solid is inhibited by more than one mechanism, that the overall resistivity $\rho$ is formed as if these resistance source ...
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Current in series circuits [duplicate]
Current is calculated according to the resistances in a circuit. Then, why is the current same everywhere in a series circuit? Shouldn't a greater current pass through the smaller resistance? I am ...
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This question was on my physics test (about basic DC circuits) [closed]
So in the following question:
Because the wire has a resistance of near 0, is there no current going through the resistor with the arrow pointing at it.
I understand that normally both resistors in ...
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Dependency of temperature acquired by a resistor on power
A nichrome heating element across 230V supply consumes 1.5kW of power and heats up to 750*C. A tungsten bulb across the same supply operates at a much higher temperature of 1600*C in order to emit ...
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Ohm's Law in Practise [closed]
When the AUX pin of a stereo is connected to my mobile phone's audio female port, I just measured the voltage at the end of this AUX pin (No load is connected) approximately 2mV using a DMM. But when ...
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Voltage and current for travel kettle
I used a 500 watt travel kettle in France last year and it tripped the electrics in my hotel room so I stopped using it. I assumed the current was too high, even though its wattage rating wasn't that ...
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Why can you assume the current remains the same after changing resistance?
In my physics textbook there is a question about a circuit:
In question b) We find out the current in the circuit is 0.003A. This is before the voltmeter is added.
In question c) a voltmeter is ...
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Why can't we add the emf of two batteries in a parallel circuit?
My teacher told me that two batteries' emf cannot be added in a parallel circuit but can be added in a series circuit. However I can't seem to fully grasp why and I think there may be some loopholes ...
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What is the ratio of the turns in the transformer when it is impedance-matching?
I study physics on my own. There is a question in my textbook:
A transformer may be used to provide maximum power transfer between two AC circuits that have diffirent impedances $Z_{1}$ and $Z_{2}...
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Why is the residual-resistance ratio (RRR) a measure of good crystalline quality?
I am currently revising a paper on a few parameters of metallic Al, and it indicates that a higher RRR is a measure of good crystalline quality. My question is why would this be the case, if having a ...
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Why does current from a grounded electrical outlet flow through me if I stay on the floor made out of a dielectric material?
Why does current from a grounded electrical outlet flow through me when I touch a "hot" terminal, if stay on the floor made of a dielectric material?
Consider an AC voltage source, such as a wall ...
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What is the magnetic field profile around an electronic resistor?
The current in a DC circuit is associated with the alignment and movement of electrons. At a resistor the free movement of electrons is inhibited, and there is a build up of electrons that creates a ...
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Two dielectric with resistivity. What is the charge distribution?
Consider two metal plates (very large). The distance between the two plates is $2a$. For the first half, the space between plates is filled by a material with dielectric constant $\varepsilon_1$ and ...
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Dependance of resistance on cross sectional area
I was wondering about a possibility......what if we take two conducting wires of the same material and the same length; both will have the same value of cross sectional area but one will be a hollow ...
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In a simple battery + resistor circuit, what form of energy is lost from the electrons upon exiting the resistor?
I will give this question a little context. Firstly, as I understand it, as soon as I "close the switch" on a circuit, electric current pretty quickly establishes a steady state where, at any given ...
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Question about deriving Resistance from data on Electric Current in Two Different Scenarios
I am preparing for an undergraduate degree in Physics, with no teacher in sight until October. The textbook I am using to prepare myself, gave me the following exercise about electric current and left ...
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Why does sticking a knife into an operating toaster give you a shock?
I understand why sticking a knife into a toaster produces an explosive phenomenon. It completes the conductive connection between the two holes in the electrical outlet and the 250 volts or so that ...
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How resistance in coils affects the damping of oscillations of a magnet through them
I performed an experiment where I connected a magnet to the end of a spring with the north side on the bottom. The magnet at the tip of the coil was aligned to pass through a column of coils of about ...
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Does $J = \sigma E $ hold when a charged mass is subjected to an external force?
Let's say that I have a charged mass that is moved by some non-electromagnetic means such as gravity or fluid flow.
I expect Maxwell's equations to hold in this case. However, I am confused as to ...
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What is the electrical difference between rolled and unrolled extension cables? [closed]
I am talking about the extension cord of length 10 meter or more as follows.
The clerk said that it is better to unroll it when using. So what is the difference? I know for alternating current there ...
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How is water a worse electric insulator than air?
I know I must be missing something here.
Water has a much higher permittivity than air, which means it has higher (distributed) capitance. That means it can more effectively convert an electric field ...
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Is there an equation for a solution's electrical conduction as temperature varies?
I'm looking for an equation that determines a solution's ability to conduct electricity as temperature varies, that hopefully could offer insight to a salt water experiment.
I did an experiment ...
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Ideal Capacitor (Introductory Physics Question)
If I have a simple setup of a open circuit with a battery (constant battery) , resistor, and uncharged capacitor, and then I close the switch of circuit, and keep it closed until the capacitor is ...
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Calculation of voltmeter reading [closed]
What will be the voltmeter reading of the circuit?
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Deviation from Linear response in metals and Ohm's law
In metals, Ohm's law is an example of a linear response i.e., $I\propto V$ where $I$ is the current (response) due to the applied voltage $V$ (external force). For metals, can we have a breakdown of ...
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What is the resultant resistance of the circuit [closed]
If all resistants have a resistance of $R$, find the resultant resistance between points $AE$.
My Try:
Since Points AB and AC have equal resistance, There's an equal current flowing through each ...
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Is ohms low violated here? [closed]
As per power equation $P=V×I$, voltage is inversely proportional to current as power of load remains constant. So why we get greater output from electrical loads with increase in voltage. (whether it ...
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