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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.
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
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
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
3
votes
Accepted
Power of an electrical equipment
The power rating only applies at a specific voltage, e.g. 110V or 240V. If you change the voltage, the equipment will consume more or less power, as determined by its resistance.
If the equipment uses …
- 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
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
2
votes
Does the resistance of the voltmeter affect the behavior of this circuit?
The internal resistance ($R_V$) of the voltmeter is in parallel with $R$. Hence, the total load resistance on the battery ($R_L$) is slightly lower, as given by$$R_L=\frac{RR_V}{R+R_V}$$
As a result …
- 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
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
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
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
Which power equation to use: $P = I^2 * R$ or $P = V^2 / R$?
You have changed the resistance from $40\Omega$ to $20\Omega$ and $60\Omega$ but did not change anything else. You must always allow for
$$V=I*R$$
If the resistance halves but the voltage stays the s …
- 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
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