Question:
A 10 V battery, a 5 V battery and a resistor R are connected in parallel.?
anonymous
2008-08-19 21:11:14 UTC
What will be the voltage across the resistor - 10 V or 5 V?

Isn't Kirchhoff's voltage law applicable to the mesh containing the 10 V battery and 5 V battery. [If we apply that we get 10-5=0 , which is false]
Four answers:
billrussell42
2008-08-20 06:49:26 UTC
Kirchoff's law doesn't apply because the circuit is not possible with ideal components. Ideal components you will have an infinite current flowing from the 10 volt battery into the 5 volt battery.



With real components, each battery has an internal resistance, perhaps on the order of 0.1 ohm, perhaps 1 ohm, perhaps 10 ohm, depending on the type and age of the batteries. If you redraw the circuit and put a 1 ohm resistor in series with each battery, then Kirchoff's law will work.





.
Al P
2008-08-20 06:55:17 UTC
For real batteries:

Assuming the battery positive terminals are

connected together, the 10v battery is charging

the 5v battery.



Let's enter the real world:Example:



R5=1 ohm internal resistance of 5v battery

R10=10 ohm internal resistance of 10v battery



Kirchhoff's voltage law:



-----electron flow in wire-->

__+10 Volt -__- 5 Volt+_

| ****************************|

| ****************************|

|___ _r10________r5___ |

******-Vr10*********-Vr5

<--electron flow in wire CW loop



10v-5v-vR5-VR10=0

10v+(-5v)+(-iR5)+(-iR10)=0



solving: i = 5/11 amps

sum of voltages: 10+ (-5) + (-5 / 11 * 1) + ((-5 / 11) * 10) = 0

terminal voltage = 9.54545455



If you add the resistor to the circuit, the net terminal voltage

will further drop. Solve for new total current.
t-kay
2008-08-20 04:39:39 UTC
no babe you are doing it the wrong way.first you should know what a resistor is and how it works



A resistor its job is to control the amount of current flowing in a circuit, and there are different sizes of these resistors therefore the voltage across the resistor depends on the resistor size you are using.If you apply 15v into circuit and you resistor allows only 3 volts that will not change even if you apply more volts into it.



hope this will help!!!!!
rscanner
2008-08-20 04:19:34 UTC
You cannot connect two ideal batteries in parallel as the current flow would be infinite.


This content was originally posted on Y! Answers, a Q&A website that shut down in 2021.
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