Finding Which Resistance and Which Circuit is Series and Which is Parallel

In summary, the conversation discusses designing a lab to determine which circuit is parallel and which is series, as well as finding the resistance of each resistor. The given equations for series and parallel circuits are mentioned and a possible solution method is suggested. The conversation also includes a tip for identifying parallel circuits and a suggestion to try different values to determine the circuit type.
  • #1
sunjay03
5
0

Homework Statement



I need to design a lab to solve for which circuit is parallel, and which is series. I also need to figure out the resistance in each resistor (each resistor is the same, so I need to find one of the resistances).

Here is the information given:
Given four identical resistors and two circuits, one in parallel, one in series, and both including two of the four resistors, which circuit is parallel, which is series, and what is the resistance of each resistor.

Homework Equations



V=IR
Series Circuit: RT=R1+R2+R3+...
Parallel Circuit: 1/RT=1/R1+1/R2+1/R3+...

The Attempt at a Solution



In the series circuit:
V = IR
R = V/I

Rresistor = R/2 (since the resistance of each resistor is the same)

The two things that I haven't been able to figure out are how I can figure out...
1. Which circuit is which (either parallel or series)
2. The resistance of the parallel circuit.

P.S. This is all DC current.

Thanks for your help! Any ideas are appreciated!

Here is a picture of the circuit apparatus, in the real lab, the box will be sealed and it will not be known which circuit is parallel and which is series.
IMG-20111117-00090.jpg

IMG-20111117-00088.jpg
 
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  • #2
Try a couple of sample values for the resistance and calculate the expected resistance you would measure for each case.

Presumably in the lab you'll be measuring the resistance of the hidden circuits and then be asked to identify which is which. The above exercise should help you see what to look for.
 
  • #3
One little tip:
When you have resistors in parallel... it does not matter how many... the combined resistance is ALWAYS less than the smallest resistor in the combination.
eg 10 + 4 +100 +6 +20 + 2 +9 + 4 in parallel must be less than 2
Not much... but I find it useful and great for catching students out!
 
  • #4
technician said:
One little tip:
When you have resistors in parallel... it does not matter how many... the combined resistance is ALWAYS less than the smallest resistor in the combination.
eg 10 + 4 +100 +6 +20 + 2 +9 + 4 in parallel must be less than 2
Not much... but I find it useful and great for catching students out!

Thanks for the reply,
Does that mean that since the resistances are equal, the one with the smaller total resistance will be the parallel circuit??
 
  • #5
sunjay03 said:
Thanks for the reply,
Does that mean that since the resistances are equal, the one with the smaller total resistance will be the parallel circuit??

Try some values and find out. Doing is the best way to learn and remember.
 

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 turn. In a parallel circuit, the components are connected in branches, so the current is divided and flows through each branch simultaneously.

2. How can I tell if a circuit is series or parallel?

A simple way to determine if a circuit is series or parallel is to look at the wiring. In a series circuit, all components are connected in a single loop, while in a parallel circuit, components are connected in branches. Another way is to use a multimeter to measure the voltage and current at different points in the circuit. In a series circuit, the voltage is divided among the components, while in a parallel circuit, the voltage remains the same.

3. How do I calculate the total resistance of a series circuit?

In a series circuit, the total resistance is equal to the sum of the individual resistances. This can be calculated using the formula: R = R1 + R2 + R3 + ..., where R is the total resistance and R1, R2, R3, etc. are the individual resistances.

4. How do I calculate the total resistance of a parallel circuit?

In a parallel circuit, the total resistance is less than the individual resistances. This can be calculated using the formula: 1/R = 1/R1 + 1/R2 + 1/R3 + ..., where R is the total resistance and R1, R2, R3, etc. are the individual resistances. To find the total resistance, take the reciprocal of the sum of the reciprocals of the individual resistances.

5. Can a circuit be both series and parallel?

Yes, it is possible for a circuit to have both series and parallel components. This is known as a combination circuit. In this case, some components are connected in series and others in parallel. The overall circuit can be simplified by first analyzing the series and parallel components separately, and then combining the results.

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