Tagged Questions
0
votes
2answers
41 views
Electric power transmission
If we want to transmit electic current for a long distance, we must minimize a heat that releases because of the resistanse. We cannot make a cable wide because it is expensive and it will be massive. ...
0
votes
1answer
43 views
Volts, Amps, and Practical Electrical Knowledge
I've heard people say that high amperage or high voltage is dangerous to humans-aren't they both? And what are the advantages to high amperage versus high voltage? And how do you generate one or the ...
1
vote
0answers
18 views
What works on 8-10 volts, 4 milli amps, and is not hardwired? [closed]
I want to know what is the smallest device that can work on a few milli amps? I know a NE-2 neon bulb works on less than 10 mAmp but on 90 volts at least.
I need to find a small device that:
1- ...
0
votes
0answers
17 views
What is the principle of active voltage balancing/equalizing device?
I am wondering about active voltage sharing devices. Their purpose is to equally divide voltages on slightly unequal super-capacitors. I found some papers like this, but it is too scientific.
I want ...
0
votes
0answers
43 views
Object accelerated by electromagnet
If I have an electromagnet (powered by a battery) and a metallic object, the
power generated will depend on the voltage of the battery and the resistance of the coil.
If I accelerate the object, will ...
0
votes
1answer
460 views
Relationship between resistance and voltage drop
In a series or parallel circuit, if two bulbs have the same resistance, do they have the same voltage drops? The problem I am asking about is below. Do A, B, and C have the same voltage drops since ...
2
votes
1answer
88 views
Which of these two methods is correct for calculating current?
I recently came across a question, for which I saw two possible methods of finding the solution. I was required to calculate the "current flowing" $I$ when given the voltage $V$, frequency $f$, total ...
2
votes
6answers
305 views
Is voltage electric potential or electric potential difference?
On Wikipedia, voltage is defined to be the electric potential difference. However, I am still not certain as to whether voltage is the electric potential ($PE/q$) or electric potential change ...
0
votes
1answer
327 views
Current without Voltage and Voltage without Current?
At school I've always learned that you can view Current and Voltage like this:
The current is the flow of charge per second and the Voltage is how badly the current 'wants' to flow.
But I'm having ...
1
vote
1answer
195 views
What kills you: Voltage or Electric current? [duplicate]
Possible Duplicate:
What causes an electric shock - Current or Voltage?
When someone gets electrocuted, what kills them; a high Voltage or a high Electric current, and why?
1
vote
1answer
146 views
What does the current vs voltage graph of a halogen look like?
I have a halogen light with a tungsten filament. It is rated 500w at 130v but I am running it from an inverter in my car that is putting out 110v. I would like to know what the actual power usage of ...
0
votes
1answer
152 views
How do I solve the current of this resistor using Maxwell's Current Theorem?
I've been trying to solve this using the method the prof. taught us, and I happen to know the answer but I can't reach it no matter how many times I've tried. The circuit in question is below:
I am ...
6
votes
2answers
262 views
How electric currents can flow between 2 points at the same potential?
According to Ohm's law, if there is a potential difference, $V$, across a resistor then there is a current, $I$, flowing through it.
Since we assume that points along the connecting wire are at the ...
0
votes
2answers
528 views
Confusion about P=VI and V=IR
If we look at $P=VI$, we see that if the current doubles then the potential difference is halved
but this doesn't seem to make sense according to $V=IR$. If we look at that equation, since the ...
1
vote
1answer
114 views
Electromotive force
EMF is defined as:
"The potential difference across the terminals of a battery or dry cell when it is giving no current to the circuit."
So, if current starts to flow from the ...
4
votes
4answers
364 views
Are square wave really square or are they always relative approximations using harmonics
I'm studying the properties of waves through different mediums, and got hung up on this.
Is a square wave always a sum of harmonics or can we produce a square wave by quickly changing voltage? Is ...
1
vote
2answers
707 views
Basic questions about voltage drop in DC circuit
I understand all the concepts of what voltage is using all the analogies but some things related to the drop of voltage across a circuit confuses me.
If I had a short circuit and attached a ...
0
votes
1answer
177 views
What does a positive gradient on a graph of V plotted against I mean in terms of EMF and internal resistance?
According to the equation $V = E-Ir$, the gradient of a graph of $V$ against $I$ should be $-r$ (internal resistance) and the Y intercept should be the EMF. Am I right?
In an experiment I used a ...
3
votes
3answers
4k views
Why do birds, sitting on electric wires, not get shocked?
If we would touch electric wires, we would get a shock, even if we are not touching ground (so that no connection is complete form wire to ground through us). I always see that birds sit on electric ...
1
vote
3answers
2k views
Finding current using EMF & internal resistance
What exactly is the difference between internal resistance and resistance?
This came up in the context of a homework problem I have been given:
The circuit shown in the figure contains two ...
3
votes
6answers
3k views
What causes an electric shock - Current or Voltage?
Though voltage and current are two interdependent physical quantity, I would like to know what gives more "shock" to a person - Voltage or Current? In simple words, will it cause more "electric - ...
1
vote
2answers
635 views
Does the 'mAh' rating of a battery have something to do with its power?
I'm curious about the 'mAh' of a battery: how can this impact the power of the battery?
I've done some research on the internet, and most of the articles I found explain about the 'amount of charge ...
2
votes
0answers
79 views
How much current would be generated by polarity reversal of Earth's magnetic field?
Continuing from my previous question Is reversal of magnetic polarity in a planet an instantaneous occurence?
A change in magnetic flux is expected to generate an EMF.
In the case where the ...
1
vote
2answers
296 views
Calculate power $P=V \times I$
I have an adapter which mentions like this...
Input: 100-240V~1.8A
50-60hZ
So how much power does it really consume?
I just knew ...
6
votes
2answers
339 views
Voltage and current of positive lightning
For a physics issues investigation I chose to investigate what effects lightning could have on an aeroplane while in flight if it was struck and then go on to discuss some possible implications of ...
1
vote
2answers
170 views
Fundamentality of voltage to current
From Ohm's Law :
Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points.
I would like to know if ...
2
votes
1answer
525 views
How does a voltage independent current source work?
So I'm having some trouble understanding what a voltage independent current source is. How can you have a current without a voltage. as I understand it voltage or EMF is the force that drives the ...
4
votes
6answers
6k views
Difference between current and voltage sources
I am confused about the current and voltage. My intuitive example would be that of a pipe of say water. The diameter of the pipe determines the amount of water flowing per second but the pressure is ...
