Parallel Circuit Voltage

[CrackBadger]

I have a really basic question. Ive read about parallel resistors lots of times but its still not clear. I know that in a parallel circuit that the voltage is the same between every parallel passage but what I was wondering is if it remains the same as the voltage of the power source or is the power sources voltage divided evenly among them?

For example
https://www.electronicsteacher.com/direct-current/series-parallel-circuits/00083.png

Lets say the power source of this circuit has an EMF of 10 volts. Would that mean theres 10 volts across R1, R2, and R3 or would the voltage be divided and there be 3 volts between R1, R2 and R3?

 

[CrackBadger]

sadf

Sorry about the title.

Anyway I was wondering about parallel resistors. This circuit for example
https://www.electronicsteacher.com/direct-current/series-parallel-circuits/00083.png

Lets say the power source of this circuit provides 10V to the circuit. Would R1, R2, and R3 have 10V across them or would it be divided among them and have 3V across them??

 

[dknguyen]

The passive sign convetion dictates that conventional current flows OUT of the + terminals and into the - terminals. Unless you are using electron flow rather than convetional current (hole flow), which isn't really used.

Now...since everything in that circuit is connected in parallel, there will be the same voltage across all of them. So since the source is the thing dictating the voltage in the circuit (10V), the voltage across all of them is 10V.

The thing that gets divided amongst the resistors is current- voltage does not flow, current does.

 

[CrackBadger]

Thats for clearing that up for me.

I've read about voltage and current in parallel and series circuits about 5 times but I still get them mixed up.

 

[dknguyen]

You can think of current is the volume of water flowing (not the speed of the water) and voltage as how hot the water is if that helps.

Any analog that uses speed of water along with volume of water starts screwing around with my mind because the volume of water is related to the speed, hehe so I don't use that one. In reality (or a more accurate simplification of reality) current is how many electrons are flowing and voltage is how energetic each individual electron is- sort of like how "hot" each electron is, or how much it's vibrating or whatever you want to call it.

 

[CrackBadger]

So you mean current flowing through a high voltage the electrons are more powerful than current flowing through a low voltage? I always pictured it as the higher the voltage the more electrons. If current is flowing between a high voltage there will be more electrons flowing in that area than an a lower voltage.

Then again that doesn't make sense because in a series circuit the more resistors the current passes the lower the voltage but the current remains the same.

 

[dknguyen]

So you mean current flowing through a high voltage the electrons are more powerful than current flowing through a low voltage?

Close enough. Rather than "flowing through a high voltage", saying that electrons "coming from a high voltage source" is more accurate when saying that the electrons are more powerful. Flowing through a high voltage [load] means more energy is removed from the electrons. But the number of electrons is still the same.

I always pictured it as the higher the voltage the more electrons. If current is flowing between a high voltage there will be more electrons flowing in that area than an a lower voltage.

Your picture is incorrect.

It's like if you were a slave driver (forgive any offsenses to this analogy but I needed one involving work done). You could either use 1 super-slave to get the work done, or use a million realy weak slaves, in the same way that you can get the same power out of a few really energetic electrons, or many less energetic electrons.

Then again that doesn't make sense because in a series circuit the more resistors the current passes the lower the voltage but the current remains the same.

True. And that's where most bad analogies fall apart.

 

[CrackBadger]

So your saying electrons driven by a higher voltage have more power than ones driven by low voltages but at the same time they travel at the exact same speed regardless of the voltage?

I don't understand where this power is coming from if its not kinetic energy or higher concentrations of electrons. What is it that separates electrons driven by different voltages if its not kinetic energy?

 

[dknguyen]

So your saying electrons driven by a higher voltage have more power than ones driven by low voltages but at the same time they travel at the exact same speed regardless of the voltage?

I don't understand where this power is coming from if its not kinetic energy or higher concentrations of electrons. What is it that separates electrons driven by different voltages if its not kinetic energy?

Yeah. THink about heat - it's kinetic energy but in random directions so it doesn't translate into speed. Just because this potato is hot doesn't mean it's flying at 1000m/s.

I am not sure of the energy in electrons. But speed doesn't realy matter. You also have to remember that these mechanical analogies aren't necessarily what happens with electricity.

 

[CrackBadger]

Damn now I get what your saying. Its like an army tank compared to a sports car. The army tank doesn't drive any faster than a sports car but it can plow through obstacles and solid objects alot easier.

Or like the difference between trying to pierce some plastic with a hot needle and a cold needle. You don't need to put more pressure on the hot needle but because its hot it has a greater ability to pierce the plastic because it melts it.

The more pressure put on these electrons the greater their ability to pass through resistors. Its weird why they don't travel faster when under pressure though.

 

[dknguyen]

Damn now I get what your saying. Its like an army tank compared to a sports car. The army tank doesn't drive any faster than a sports car but it can plow through obstacles and solid objects alot easier.

Or like the difference between trying to pierce some plastic with a hot needle and a cold needle. You don't need to put more pressure on the hot needle but because its hot it has a greater ability to pierce the plastic because it melts it.

The more pressure put on these electrons the greater their ability to pass through resistors. Its weird why they don't travel faster when under pressure though.

It's like quantum mechanics to newtonian mechanics.

 

[Nigel Goodwin]

By simply looking at that picture it's pretty obvious that the battery connects directly across each resistor - so each resistor MUST have the battery voltage across it. In parallel (like that) each resistor has the same voltage, but the current is divided between them (depending on the resistor values - if all are the same, then each has an equal current).