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Results tagged with electric-current
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user 8234
A measure of the rate at which electric charge is transported (especially through a circuit), it has units of charge/time.
1
vote
Root mean square value for DC
AC performs work when the voltage is negative, as well as when it is positive. This means that the "average" is an invalid measure for current or power. Instead, RMS is used.
With RMS the quantity is …
- 11.2k
2
votes
Accepted
Current or Current Density?
It's the current density $J$ that changes.
Current is defined as an amount of charge per seconds, $I=Q/T$, i.e. a number of electrons flowing through the wire every second. Once your conductor is co …
- 11.2k
4
votes
Accepted
Why does holding an electrical switch in between on and off states cause sparks?
The switch really has 2 positions: on and off.
However, when you move the switch very slowly, it may leave the closed position slowly. When the switch is just barely open, the field may cause the air …
- 11.2k
1
vote
Does alternating current come from DC?
AC can be made from DC, and vice versa. DC is a steady voltage, with AC the voltage fluctuates from negative to positive and back, many times per second.
Most electricity generators generate AC. The …
- 11.2k
1
vote
Accepted
Does the brightness/power of each individual bulb change when you add more bulbs in a parall...
Assume that there is an ideal voltage source
The problem is that such a voltage source does not exist. Every real-life voltage source has an internal resistance. Because of that (and possibly for …
- 11.2k
3
votes
Accepted
Science of Short Circuits
You ignore the fact that the lightbulb's resistance is in parallel with that of the short circuit. And both of these are in series with the battery's internal resistance.
Let's make the assumption th …
- 11.2k
1
vote
Can i take a high voltage system and a high amp system and merge them?
No matter how you connect them, the high voltage source will not be able to provide the 50A. If it could you would have 50A @ 30kV, i.e a 1.5 MW power souce!
The best you can hope for is the availab …
- 11.2k
1
vote
Grounding on the wooden floor
No, you will not get an electric shock, but I strongly advise against trying it.
Electric potential is a relative measure. There is nothing with "0V"; all you can say is that one terminal has 0V pote …
- 11.2k
1
vote
Electric shock from a frayed wire
$20V$ is not normally dangerous. You may not even feel it.
It is not the voltage that causes danger, but rather the current it generates through your body. Anything over about $10mA$ will be unpleas …
- 11.2k
10
votes
Will a bulb glow brighter if voltage is increased but current remains the same?
Without changing the characteristics of the light bulb, it's not possible to change the voltage if you want the current to stay the same. When the voltage is increased, the current through the bulb ha …
- 11.2k
0
votes
Accepted
Current flow with batteries in series vs parallel
Using the height analogy, tripling the height of the water reservoir means that you will also get 3 times the pressure in the pipe. That increased pressure then increases the flow through the pipe.
M …
- 11.2k
1
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Joining two insulators at different potentials with a conductor
The wire will equalise the potential between the contact points on the insulators. It cannot do any more than that, because the insulators will not conduct. Because they cannot conduct, charge cannot …
- 11.2k
1
vote
Why the potential at positive terminal is considered to be high?
I hope I understand your question correctly.
This is all caused by the fact that the "positive" and "negative" labels were assigned long before the electron was discovered.
Back in the early 1700s it …
- 11.2k
1
vote
Why is EMF equal to PD when circuit is "open"?
As you stated, we can think of a real battery as an ideal one with an internal resistance $R_i$. This battery is then connected to an external circuit with resistance $R$. Those 2 resistors form a vol …
- 11.2k
2
votes
How can "...electrons flow in metals, but not in the ground..." explain grounding rods?
You are correct, electric current consists of electrons travelling from one place to another. Some materials conduct electricity better than others. Copper is one of the best and that's why our conduc …
- 11.2k