Why does the voltage increase when batteries are connected in parallel?

infinity_production2017-07-23 16:46:55

Electronics

infinity_production, 2017-07-23 16:46:55

Hello wrold!
Why does the current increase when batteries are connected in parallel, but the voltage does not increase?
If voltage = current * resistance, then as the current increases, the voltage should also increase. What law affects this and why does this happen (in simple words, please, as for a 6-year-old child, as Einstein advised)?

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6 answer(s)

Viktor, 2017-07-24
@infinity_production

All this is easily explained even to a child, if we use the analogy with the flow of water. The current is (roughly speaking) the thickness of the jet or the flow of water in this jet, and the voltage is the pressure under which this jet flows. You can also interpret the voltage as the difference in water levels - say, on one and the other side of the dam: the larger it is, the stronger the jet hits the turbine blades of the hydroelectric power station.
From this analogy, it is easy to see that the head does not change when the thickness of the jet (i.e., the flow rate) is increased or decreased - for example, punching another hole in the dam next to the previous one. As long as the water supply is sufficient, the flow of water through the first hole will not change when the second hole appears. And vice versa, by changing the pressure, it is possible to change the water flow in the jet, even if the hole in the dam remains the same diameter.
Well, guess what electrical parameter this hole is analogous to.

Fixid, 2017-07-23
@Fixid

It looks like + there is an answer to your question
Why does the current increase when batteries are connected in parallel?

pfg21, 2017-07-23
@pfg21

the battery can only create a certain potential difference at its terminals, it directly depends on the electronegativity of the electrode materials.
thus in the circuit it manifests itself as a source of voltage and in the connected resistance, due to the potential difference generated by the battery (ideally a constant value), a current flows inversely proportional to the resistance value.
your reasoning would be true for a current source - i.e. regardless of the resistance, it generates the same current, then the potential difference across the resistance will be proportional to its value.

Garik_Shuster, 2017-07-24
@Garik_Shuster

If voltage = current * resistance, then as the current increases, the voltage should also increase.

If the current strength began to grow, then the resistance has changed. This is Ohm's law. In your case, the voltage is a constant value, everything else changes. Those. the calculation is based on the fact that the power supply itself cannot change the voltage (unless the battery "sits down").

klopina, 2017-07-23
@klopina

"Tension" is what they usually say. A real and correct "drop" voltage. Voltage drops occur when the circuit is closed and current flows through it, then U=i*r. When the battery is not connected it is the source of EMF and not voltage. When connected and current flows, the voltmeter on the battery will show the EMF of the battery minus the voltage drop on the battery and it (the voltmeter reading) is equal to the sum of all voltage drops in the circuit i.e. the sum of all resistances in series and parallel.

stasserov, 2019-11-05
@stasserov

I will answer as Einstein would have answered. Let's take, well, let's say, three three-liter cans of water, put them side by side, let down a tube of water from each can, and mentally imagine that water flowed through them with some miraculous force. Water will flow at the same speed through all three tubes, since the "voltage" of each can is its own equal to 1 can. But if you calculate how much water will pour out, then of course there will be more of it, because the water goes not through one tube, but through three. Summing up three tubes, we get a current strength equal to three tubes, is there more current? Yes, more! Current \u003d 3 tubes, the resistance is less than if the water went through one tube. The voltage remained the same on each jar, so the speed of the passage of water did not increase, compared with one tube and a jar. Now let's increase the voltage on the banks, putting them next to each other, the voltage did not increase, we understood this, then we mentally put each jar on top of each other in a column. The tension in the lower bank became stronger noticeably. Let's lower the tube from the lower jar, what will happen? Water will flow through one tube, the voltage has increased, but there is only one tube, the resistance of the tube does not allow the current to roam, so it has to pass through a narrow passage as it turns out. Here, of course, not the tubes themselves play a big role, you need to understand, but the banks themselves. Mentally remove the tubes and immediately, I think, everything will become clear why, with a parallel connection, the voltage does not change, but the current increases, and why, with a series connection, the voltage increases, and the current, although it changes, but not like in the case of a parallel connection. then mentally put each jar on top of each other in a column. The tension in the lower bank became stronger noticeably. Let's lower the tube from the lower jar, what will happen? Water will flow through one tube, the voltage has increased, but there is only one tube, the resistance of the tube does not allow the current to roam, so it has to pass through a narrow passage as it turns out. Here, of course, not the tubes themselves play a big role, you need to understand, but the banks themselves. Mentally remove the tubes and immediately, I think, everything will become clear why, with a parallel connection, the voltage does not change, but the current increases, and why, with a series connection, the voltage increases, and the current, although it changes, but not as in the case of a parallel connection. then mentally put each jar on top of each other in a column. The tension in the lower bank became stronger noticeably. Let's lower the tube from the lower jar, what will happen? Water will flow through one tube, the voltage has increased, but there is only one tube, the resistance of the tube does not allow the current to roam, so it has to pass through a narrow passage as it turns out. Here, of course, not the tubes themselves play a big role, you need to understand, but the banks themselves. Mentally remove the tubes and immediately, I think, everything will become clear why, with a parallel connection, the voltage does not change, but the current increases, and why, with a series connection, the voltage increases, and the current, although it changes, but not as in the case of a parallel connection. the voltage has increased, but there is only one tube, the resistance of the tube does not allow the current to roam, so it has to pass through a narrow passage as it turns out. Here, of course, not the tubes themselves play a big role, you need to understand, but the banks themselves. Mentally remove the tubes and immediately, I think, everything will become clear why, with a parallel connection, the voltage does not change, but the current increases, and why, with a series connection, the voltage increases, and the current, although it changes, but not as in the case of a parallel connection. the voltage has increased, but there is only one tube, the resistance of the tube does not allow the current to roam, so it has to pass through a narrow passage as it turns out. Here, of course, not the tubes themselves play a big role, you need to understand, but the banks themselves. Mentally remove the tubes and immediately, I think, everything will become clear why, with a parallel connection, the voltage does not change, but the current increases, and why, with a series connection, the voltage increases, and the current, although it changes, but not as in the case of a parallel connection.