# What am I actually missing?

While I was reading a physics textbook, I've seen something unclear, which is about ΔV. What does this book actually mean by ΔV? It seems like it is potential difference, right? However, the thing I'm trying to get is why it is potential difference, assume that there are two batteries connected in series or parallel, How should we analyze the circuit? Honestly, I didn't see anything related to parallel/series batteries, Why? On other hand, it should've explained what to do when there are batteries connected in series or parallel. What am I missing?

Wishing My Kindest Regards!

EDIT:

• The information is probably obvious from the figure. Mar 25, 2018 at 19:17
• @SpehroPefhany that would be as you said. However, this textbook should've explained what to do when there are batteries in parallel or series. Otherwise, thinking on If I'm missing something while searching. Does ΔV mean potential difference of battery or something?
– Busi
Mar 25, 2018 at 19:20
• Is there someone who's able to help? :)
– Busi
Mar 25, 2018 at 19:43
• Delta signifies difference, and delta-V signifies a voltage difference, between two nodes in a circuit, two places where a voltmeter probe can be pressed to make a measurement. So, delta-V indicates a voltage difference for some (any) two-terminal component or subcircuit. Mar 26, 2018 at 4:56

Any time you have current flow anywhere in a circuit it creates delta-v, which means differential voltage. Any 2 points in a circuit with current flowing will create a delta-v. Resistors and even a long copper trace create a voltage drop, also called delta-v.

Current flow is constant in a single loop of power source, resistance and load, but using a voltmeter you will find a delta-v across any 2 points in the circuit.

All delta-v's in series add together to create a large delta-v. Any resistance via resistors or wire length create delta-v that adds up to the power source voltage/potential.

The batteries are also delta-v objects, but they create potential with chemicals.

• Does it mean that we will sum up the batteries if they're connected in series?
– Busi
Mar 25, 2018 at 20:10
• Parallel batteries sum the current that can be drawn from them, but maintain the same voltage. Batteries in series add their voltages together but supply the same current as one battery.
– user105652
Mar 25, 2018 at 20:12
• So did it explain what you said by delta V?
– Busi
Mar 25, 2018 at 20:13
• Yes. I did not contradict myself. Poke into circuits with a voltmeter and find out these things.
– user105652
Mar 25, 2018 at 20:14
• Oh, I mean by Delta V = delta V_1 = delta V_2 However, it doesn't seem like It explained, why? It is just potential difference, isn't it?
– Busi
Mar 25, 2018 at 20:14

Okay, the figure is not very clear. Delta-V is the voltage across the respective resistor. So by Kirchoff's voltage law the drops across each component add up to zero, taking polarity into account.

There is only one battery, as is clearly shown, but two resistors in series. Please add the figure to the question.

• That's not the answer I'm looking for. It doesn't matter if I've attached figure or not. The thing is to get what ΔV means.
– Busi
Mar 25, 2018 at 19:22
• You're being very belligerent for someone who is looking for help. Mar 25, 2018 at 19:24
• Definelity not :) just mentioning what I'm having trouble with. If I seem like rude, my apologies.
– Busi
Mar 25, 2018 at 19:30
• "The thing is to get what ΔV means." spehro answerd "Delta-V is the voltage across the respective resistor". I don't get how that can not be a good answer! Mar 25, 2018 at 19:44
• (And the request to add the picture is to make your question a better question.) Mar 25, 2018 at 19:45