Tagged Questions

0
votes
2answers
74 views

What happens when non-equal voltages are put in parallel? [duplicate]

If two batteries, say 2 volts and 5 volts, are connected in parallel, are there any problems? The higher voltage will then want to flow out, but also towards the lower 2 volt battery end, right?
0
votes
1answer
46 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 ...
0
votes
1answer
115 views

How electrons act under rotating magnetic field?

I study Power Engineering in University. Today I asked my lecturer to explain me exactly how atom's electrons act under spinning rotor's magnetic field, that generated dynamic electricity. But he even ...
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
4answers
137 views

Why is there a potential difference?

The question then asks for the potential difference between $X$ and $Y$, which is claimed to be $3.6\text{ volts}%$. Why would there be a potential difference in this case? If I connect a lightbulb ...
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 ...
1
vote
1answer
197 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?
3
votes
2answers
254 views

How can you have a negative voltage?

How can you have a negative voltage? I don't really understand the concept of negative voltage, how can it exist?
1
vote
1answer
147 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
2answers
552 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
116 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
371 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
716 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
178 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 ...
4
votes
1answer
197 views

why sometimes touching old flickering tube lights starts them properly

In my old house there are two old tube lights. Some times they don't start properly, (specially at evening time, may be it is because of low voltage), they starts flickering i.e. on and off ...
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 - ...
0
votes
0answers
86 views

what exactly do electric waves transfer from one point of the wire to other..? [duplicate]

Possible Duplicate: how does electricity propagate in a conductor? so basically i was considering the speed of the charges inside wire defined by the drift velocity and speed of electric ...
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 ...
0
votes
1answer
171 views

Emf Of a Cell in a common circuit

My questions will be based on the above figure. The Emf Source V1 and R1 Together form a cell(R1 is internal resistance) R2 Represents the entire load on the source VoltMeter My teacher told ...
1
vote
2answers
171 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 ...
1
vote
3answers
549 views

Why does the potential drop across a battery and resistor equal the emf of the battery?

In this diagram you can see the potential difference across the battery and resistor is the same as the pd created by the battery (the battery and resistor are representing a battery with internal ...
2
votes
1answer
530 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 ...
2
votes
2answers
556 views

is the voltage drop of a battery that is being short circuited the same as the battery's advertised voltige

So I know this is a pretty fundamental question, but I'll ask it any way. lets say you have a 12V battery, and the positive is connected to the negative directly by a wire with negligible ...
0
votes
2answers
311 views

How can you measure battery output to see if the wattage is accurate? [closed]

When you have a battery and it shows you the milliamperehours and volts. You can use those to calculate the wattage. How can you test the battery to see if its wattage is accurate or if the company ...
0
votes
0answers
50 views

How can I figure out how many kWh's are in a battery using the mAh's and voltage. [duplicate]

Possible Duplicate: Relating milliampere-hours to watt-hours for batteries How can I figure out how many kWh's are in a battery using the mAh's and voltage. Some batteries only list mAh's ...
1
vote
5answers
292 views

How do electrical devices suck electricity?

If the electric potential is 220V and some device needs 1500watts then how does it suck exactly that amount of electrical energy from outlet?
2
votes
5answers
438 views

Why doesn't an electron accelerate in a circuit?

Why don't electrons accelerate when a voltage is applied between two points in in a circuit? All the textbooks I've referred conveyed the meaning that when an electron traveled from negative potential ...
2
votes
2answers
732 views

Voltage and Current in transformers

In transformers, the ratio of the voltages equals the ratio of the turns - so double the output coil's turns and the output voltage doubles. Then, in order to conserve energy, current halves. This ...
8
votes
8answers
3k views

What is the difference between electric potential, voltage and electromotive force?

This is a confused part ever since I started learning electricity. What is the difference between voltage and electromotive force (emf)? Both of them have the same SI unit, right? I would appreciate ...
2
votes
1answer
1k views

When does voltage drop occur?

Why or when does it occur in a circuit? What does it imply when you speak of a voltage drop across a resistor? (Obviously, it probably means that the current's voltage before the resistor is higher ...
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 ...