All Questions
Tagged with electricity voltage
396 questions
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What is the difference between electric spark and electric arc?
In my student book they separate these two and indicate that sparks need high voltage to occur while arcs need low voltage with normal or low pressure and electric arcs CAN come with heat and bright ...
- 59
0
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2
answers
324
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Why current drops when voltage increases?
https://www.youtube.com/watch?v=ubZuSZYVBng&t=329s
In the video above the man put a 200 thousands volt ball near a non-charged one and a very tiny current appear between them. But I think with ...
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8
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4
answers
52k
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Why don't we get a shock touching neutral wire?
Neutral wire has a V same as ground i.e almost 0. Also it carries some current. So if we touch the wire don't we to become a part of the circuit? Even if we are on the ground and current should flow ...
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0
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2
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152
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Electrical energy (J) from voltage (V), amperage (A) and exposure duration (s)
I have that the electrical energy $E$ in Joules (J) is equal to $E = time \times current^2 \times resistance$.
Reasoning with SI units, we can verify that this equation does return energy values in ...
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0
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2
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838
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How does current flow through the earth and back to the supply to break the fuse?
From my textbook, it says when the live wire touches the metal casing, a current will flow to the earth and blow the fuse located in the live wire. But through what devices will the current flow after ...
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0
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1
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273
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Power and power loss during transmission of power
So let's say power to be delivered to homes is 80 kW($P_3$ = 80 kW) and the houses have to receive it at 220 V ($V_3$ = 220 V). The substation is a 4000 V to 220 V step-down transformer and $R_2=15\ \...
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1
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1
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999
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Why are we even interested in solar cells under bias voltage?
I couldn't find any answer on this super basic question.
Some people on the internet say that you would not put a solar cell in an array under bias, others say that they bias themselves, but I don't ...
0
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1
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47
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What exactly is voltage in this case?
My textbook states the following:
Voltage is the same across each component of the parallel circuit.
However I am confused on what the exact meaning of voltage is in this case, is voltage used ...
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0
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2
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669
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Why does the capacitor charge through a resistor?
I was working on a question where there was a circuit and the switch was open, there was one capacitor and one resistor. It said: immediately after the switch is closed, what is the current in the ...
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0
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1
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766
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What does the labelling of a conductor such as: 24 W 12 V mean? Does this mean the resistance of the wire or the current?
So I came across a question where a lamp was labelled 24 W and 12 V. 2 lamps that were identical and had this labelling were then put in series with a voltage supply of 12 V.
Obviously the individual ...
- 220
2
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2
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671
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Ohm's law and Joules heating
Ohm's law state that the ratio of V and I gives us a constant value of R provided that the temperature is kept constant throughout. However, in accordance with the joule's heating it would get heated ...
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0
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1
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Will an appliance metal case get alive if touched by the neutral wire?
My phyiscs textbook only discusses what will happen if a live wire touches a metal case and how it turns alive, however, I was wondering, will the same effect happen to the metal case if touched by ...
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1
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1
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622
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Direction of flow of Electrons during an Electric Shock
Question:
What is the direction of the flow of electrons during an electric shock?
I was studying electrostatic force, suddenly a question struck my mind “What will be the direction of flow of ...
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0
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1
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229
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Why the potential at positive terminal is considered to be high?
even though it's the electrons that move from negative terminal of the battery and gets move along the external circuit and finally enters the positive terminal of the battery and due to battery force ...
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2
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Why are voltage and volt both are denoted by $V$? [closed]
Why are voltage and volt both are denoted by $V$? Won't it cause confusion?
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2
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Wouldnt the electric potential energy be constantly decreasing in a circuit and not just at points of resistance?
Good day,
I am a beginner in electrical engineering.I was wondering when the positive charge is passing through the circuit isn’t it constantly losing electrical potential energy as it is flowing from ...
0
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1
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81
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How do charges away from the terminal react when the switch is flipped on?
Let us say we have a simple purely resistive DC circuit. When we flip the switch a current starts flowing which after some time becomes constant. Now, I know that the electric field across difference ...
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1
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0
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875
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How does a battery create potential difference? [duplicate]
I'm in year 10 (9th Grade for the Americans) and I just had a question about physics.
How does a battery create potential difference?
It it because the electrons are gaining energy as they get pulled ...
user272011
1
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1
answer
53
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Differences between $V_{ab}$, $\Delta V$, $\Delta V_{ab}$, $\Delta V_a$ and $V_a$
$V$ is electric potential.
From my understanding of these notations
\begin{align}
V_{ab}&=V_a-V_b\\
\Delta V&=\Delta V_{ab}=V_b-V_a;\text{consider $a\to b$}\\
\Delta V_a&=V_a=V_a-V_\infty
\...
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-5
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2
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123
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Voltage about potential difference
Can someone explain to me all about potential difference. It is basically taught when teaching about voltage but I want to know all about potential difference.
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2
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368
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When to use Ohm's law as opposed to using power formula?
I am a mechanic trying to gain a better understanding of electrical theory on vehicles. I have a sound understanding of Ohm's law and also the power formula (Power = Voltage x Current)
However, I am ...
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5
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1
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229
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What does the term 'high voltage' really mean?
This might be a dumb question but i am not so familiar with the word voltage:
What does the textbooks really mean when they say high voltage?. Does that mean:
There are more charges so more voltage, ...
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8
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4
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2k
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What's the point of an RMS value? [duplicate]
the RMS (root mean square) value of $f(x)$ is defined as:
$$f(x)_{rms}=\sqrt{\frac{\int^b_a (f(x))^2dx}{b-a}}$$
Why do we do this very specific thing of taking the square, the mean, and then the ...
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2
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2
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280
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Why doesn't electric potential decrease gradually across a wire?
Let's assume that the resistance of a wire is zero. Now, suppose the wire has a length of 10 m and is connected to a battery with an emf of 10 V. According to my physics textbook, the electric field ...
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0
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1
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801
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Current flow in potentiometers
In the following circuit involving a potentiometer;
Assume $V$ to be the voltage produced by the cell in the primary circuit across the length $AJ$ of the potentiometer wire, and $E$ to be that ...
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3
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4
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5k
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How much current will go through my body if I were to put my finger in an outlet?
i know this is a silly question, but i couldn't manage to wrap my head around it. I am kinda new to electronics.
My home's outlets provide 220V. Upon doing some (a lot) research, the current that ...
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0
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1
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105
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What's the source of voltage? [duplicate]
I've been told that in a DC circuit with a battery the negative terminal of the battery "pushes" electrons in nearby atom away of it and those by themselves cause electrons in other atoms to move, but ...
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1
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3
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685
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What is meant by transmission voltage?
I had a question in class that went :
$120$kW of power is generated at a power plant and is then transmitted. The resistance in the transmission lines is $0.4 \Omega$. Calculate the power lost as ...
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2
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1
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606
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Power loss in power cable contradiction
To minimize the power loss in long-distance power cables it is best to minimize the current and maximize the voltage. This is because the power loss in the cable is calculated by $P=VI$, which we can ...
user260791
0
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2
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875
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Energy Loss in Resistors [duplicate]
What kind energy of electrons is lost when current passes through a resistor?
OR
What happens to electrons when they pass through a resistor?
Does current decrease when its passes through a ...
0
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3
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12k
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Why does increasing voltage increase current? [duplicate]
If we increase voltage, we are increasing energy per coulomb. How does it increase the number of coulombs per second (current)?
1
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2
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258
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Why does the current stay same everywhere in a series circuit [duplicate]
Current in a series circuit are the same everywhere, but when there is a bulb creating a potential difference, wouldn't the rate of the same number of electrons flowing, coming out from the bulb ...
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1
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1
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307
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Is there a potential difference across the bulb after current passed through a diode?
I understand that voltage can exist without current so what I want to ask is will there be a potential difference across the bulb(situated after the diode) when a batteries supplied energy through a ...
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2
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Why does breakdown voltage increase with pressure in gas insulators
There are two main theories which I have been reading into Townsends avalanche effect and Paschen's curve.
I understand that as electrons move from negative to positive electrode they collide with gas ...
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-1
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3
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96
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Current and voltage - Incompatibility between Ohm's Law and Power Law! [duplicate]
Ohm's Law: I $=\frac{V}{R}$: Increasing voltage increases current.
Power Law: P $={V}*{I}$: Increasing voltage decreases current.
Am I missing something?
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3
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710
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Would there be a potential difference across a cell connected with just a wire in complete circuit?
My textbook says, that across a battery or a cell there should be a potential drop equal to its e.m.f.
Now consider a simple circuit with a cell of e.m.f 9 V. Let us assume a point on the negative ...
user248823
5
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1
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How are electric and magnetic fields able to travel through space and wires, and how are they more than mathematical constructs?
Once I was taught that light is physically made up of in-phase E and B fields oscillating perpendicularly, it was a little baffling because I always thought fields were just analysis tools (or even ...
-1
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1
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220
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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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0
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3
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99
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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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0
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3
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320
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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 ...
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1
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0
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24
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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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3
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Does an electric current flow in an open circuit?
When the positive and negative terminals of a battery is connected through a wire, an electric current flows across the circuit. Generally, electrons are the ones that flow (from negative terminal to ...
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9
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How does the current remain the same in a circuit? [duplicate]
I understand when we say current, we mean charge (protons/electrons) passing past a point per second. And the charges have energy due to the e.m.f. of the power supply.
Now tell me, if a lamp has ...
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3
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1
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172
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How does the voltmeter measure the resistance of the component to measure?
This is a very newbie question I guess, but I really did not find any answer on the internet that satisfies me, so here I am.
I know that to measure voltage, we use $V=I \cdot R$
How does the ...
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0
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1
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269
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Voltage as the work to move from infinity to a point in field
I understand that electric potential is defined as the work needed to move a charge from infinity to a specific point in the field.
However, how does this apply for a field which is limited between ...
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1
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1
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159
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Thevenin-Norton Conversion
Using Thévenin-Norton equivalence, prove that the circuit below
is equivalent to the circuit below
The main point behind my confusion is that the current source has no parallel resistance. As a ...
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2
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265
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Voltage in a shortcircuit connected in parallel to a voltage source and two resistors [closed]
I am trying to calculate the voltage in A, in the following circuit:
That means I have to calculate the voltage at the ground end relative to A, or with other words: "go from ground to A and add or ...
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0
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1
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47
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Does $\frac{V}I = k$ necessarily imply that the wire follows Ohm's Law?
Does $\frac{V}I = k$ necessarily imply that the wire follows Ohm's Law?
https://i.sstatic.net/ClEqP.jpg
Say, for a range of about 15 Volts, I get a good $\frac{V}I = k$ result, after which the ratio ...
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0
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1
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654
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Understanding the physical meaning and effect of voltage and current being out of sync
In alternating current, we may have inductors and capacitors which make voltage and current become out of sync.
At the beginning, I was stuck because how can it be that there is first voltage and ...
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0
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2
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752
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Convention for expressing voltage between two points
Voltage is always related to two points, because it means a difference in electric potential, between two points.
If we want to express the voltage between A and B, we could say:
The potential at ...
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