Single battery & Single resistor: Series or parallel?

In summary, a circuit can have components that are in series, parallel, both at the same time, or neither. These are just different ways to view the circuit and help analyze it. The general rule is that components in parallel have the same voltage across them, while components in series have the same current through them. The internal resistance of the battery and wires may be negligible in some cases, but it becomes important to consider in circuits with higher power flows.
  • #1
JJBladester
Gold Member
286
2

Homework Statement



Can a circuit be both series and parallel? Not series-parallel, but series *and* parallel?

Let's say you have a battery with its positive terminal connected to a resistor and its negative terminal connected to the other end of the resistor.

Due to conservation of charge, the circuit is in series. Due to the resistor being connected directly across the battery, it has the same voltage as the battery and thus it is in parallel with the battery. Right?

So the circuit exists in both a series state and a parallel state...?
 
Physics news on Phys.org
  • #2
The battery has an internal resistance as does the resistor leads so the circuit is a serial resistance circuit. The voltage across the resistor will very close to the same voltage as the battery only as long as the value of the resistor is high compared to the other series resistance values.
 
Last edited:
  • #3
So the circuit exists in both a series state and a parallel state...?

Correct. A circuit can have components that are in series, parallel, both at the same time or neither. They are only ways to view a circuit (or parts of a circuit) to help analyse it.
 
  • #4
CWatters said:
Correct. A circuit can have components that are in series, parallel, both at the same time or neither. They are only ways to view a circuit (or parts of a circuit) to help analyse it.

This question has bugged me since I started my B.S. in EET. I was too afraid to ask it because it seemed "elementary". Thanks for the confidence boost. :)
 
  • #5
Just to add it's quite common to change your view of how a circuit is configured... For example in this circuit when the switch is made you might choose to analyse the R and C as being in parallel with each other and the battery. Then when the switch is opened it makes more sense to view the C and R as being in series with each other.

A general rule is that

Components in parallel have the same voltage across them.
Components in series have the samecurrent through them.
 

Attachments

  • series.png
    series.png
    910 bytes · Views: 415
  • #6
CWatters said:
A general rule is that

Components in parallel have the same voltage across them.
Components in series have the same current through them.

I would look at the problem using Kirchoff's "Loop" Rule with a "real battery".
http://www.physics.ucdavis.edu/~savrasov/Projects/Teaching/2002FallPhys121/ProblemSolving3.pdf
http://www.physics.ohio-state.edu/~kass/P132/P132_ch28.pdf
 
Last edited:
  • #7
nsaspook - I'm not sure what point you are making by raising the issue of the internal resistance of the battery?

I think it's quite reasonable to decide that in some cases the internal resistance of the battery is negligible and that allows you to treat components connected to the battery as being in parallel with it.

Real world wire also has resistance and if you had to take that into account all the time you could never wire up anything in parallel.
 
  • #8
CWatters said:
nsaspook - I'm not sure what point you are making by raising the issue of the internal resistance of the battery?

I think it's quite reasonable to decide that in some cases the internal resistance of the battery is negligible and that allows you to treat components connected to the battery as being in parallel with it.

Real world wire also has resistance and if you had to take that into account all the time you could never wire up anything in parallel.

It might be reasonable to assume that (being in parallel) but I just think it's a sloppy way of viewing a simple loop circuit of series connected components. Once you start dealing with circuits with power flows greater than a few hundred watts the "negligible" series resistances become critical factors and it becomes important to use the correct methodology even with a simple thing like how to connect a wire for best battery performance with true parallel circuits.

http://www.smartgauge.co.uk/batt_con.html
 
Last edited:

1. What is the difference between a series and parallel circuit?

In a series circuit, the components are connected in a single loop, so the current flows through each component in sequence. In a parallel circuit, the components are connected in multiple branches, so the current is divided among them.

2. How does the voltage and current change in a series or parallel circuit?

In a series circuit, the voltage drops across each component, so the total voltage is equal to the sum of the individual voltage drops. In a parallel circuit, the voltage is the same across each branch, but the total current is equal to the sum of the individual branch currents.

3. Which circuit arrangement is better for powering devices - series or parallel?

It depends on the type of device and its power requirements. Series circuits are better for devices that require a specific voltage, while parallel circuits are better for devices that require a specific current.

4. How does the resistance affect the overall circuit in a series or parallel arrangement?

In a series circuit, the total resistance is equal to the sum of the individual resistances. In a parallel circuit, the total resistance is less than the smallest individual resistance.

5. What happens if one component in a series or parallel circuit fails?

In a series circuit, if one component fails, the entire circuit will stop working. In a parallel circuit, the other branches will still function, but the overall current will decrease.

Similar threads

  • Introductory Physics Homework Help
Replies
4
Views
207
  • Introductory Physics Homework Help
Replies
20
Views
254
  • Introductory Physics Homework Help
Replies
3
Views
192
  • Introductory Physics Homework Help
Replies
6
Views
225
  • Introductory Physics Homework Help
Replies
24
Views
4K
  • Introductory Physics Homework Help
Replies
5
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
871
  • Introductory Physics Homework Help
Replies
3
Views
896
  • Introductory Physics Homework Help
Replies
4
Views
2K
  • Introductory Physics Homework Help
Replies
5
Views
1K
Back
Top