# Determine the effective resistance of the two resistors in series

• xswtxoj
In summary: If the line is not linear, then the resistance is not in ohm's law.If I have the measured series as 146.7 and 31.7 as parallel, and the total equivalent resistance is 47 & 100then would i calc. (2.3- 1.3)/ (.05-.03) = 50
xswtxoj

## Homework Statement

well first its to plot the graph ( volt vs. current) then determine the effective resistance of the two resistors in series. 2nd compare the effective resistance of the resistors in series with the resistances of each resistors.

R=V/I

## The Attempt at a Solution

Based on this chart: then graph
Voltage (Volts) Current (Amps)
3.24 .021
9.32 .060
14.67 .095
20.3 .123
8.2 .056
15.4 .106

R= V/I 3.24/.021 = 154.3
15.4/.106 = 145.3

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xswtxoj said:
Compare the effectiveness resistance of the two resistors in series of each resistor

That sentence makes no sense at all. Can you please carefully type out the problem exactly as it appears in your lab handout?

I assume you mean "effective resistance of 2 resistors in a series circuit" in which case you simply add them up

Sure, that's how you compute them. But the OP says compare. What is he supposed to compare them to?

well first its to plot the graph ( volt vs. current which i did) then determine the effective resistance of the two resistors in series. 2nd compare the effective resistance of the resistors in series with the resistances of each resistors.

Last edited:
OK, so do you know how to get the effective resistance from the plot of voltage vs current?

pick 2 coordinate points and find slope, where slope = R

I wouldn't just pick 2 points, but rather the best line that fits all of the data. If you haven't learned about that (linear regression that is) then I would just compute the resistance for each data point and then average them. That will be the effective resistance.

can u pick 2 point from graph on the line and find slope? then once you find the effective resistance, then compare the effective resistance of the resistors in series with the resistances of each resistors?

Like I said, I wouldn't pick just two points. If you do that then you aren't taking all of the data into account.

but in general to find resistance using ur data points do u do V/I = R or v2-v1/I1-i2 for a single resistor?

Only if you have 2 data points. If you have more then they must be included somehow.

If I have this
Data Table 2: The Voltage vs. Current for a Single Resistor Circuit
Current V
0.01 0.5
0.02 0.8
0.03 1.3
0.04 1.8
0.05 2.3

then would i calc. (2.3- 1.3)/ (.05-.03) = 50

Can't you see that if you use only those two data points that you're ignoring the rest of the data?

so i have to calculate each indivudual points?

I said that 8 posts ago.

Resistances

## Homework Statement

well first its to plot the graph ( volt vs. current)
then
1. determine the effective resistance of the two resistors in series.
2nd compare the effective resistance of the resistors in series with the resistances of each resistors.

2. Homework Equations

R=V/I

3. The Attempt at a Solution

Based on this chart: then graph
Voltage (Volts) /Current (Amps)
3.24 /.021 =154.3
9.32 /.060 = 15.53
14.67 /.095 = 154.4
20.3 /.123 =165.0
8.2 /.056 =146.4
15.4 /.106 = 145.3

I divided (v/I = r)

so far I don't know how to continue.

I've merged your two threads. In the future please do not start multiple threads for the same question. It is not necessary and is considered spam.

so far I don't know how to continue.

I told you exactly how to continue in Post #8.

so for series i calculate each individual then add all the R's and get the average, is it the same for parallel too?

Yes, I would do the same for parallel resistance.

compare the effective resistance of the resistors in series with the resistances of each resistors. I used resistors 47 and 100, and for series I got 153 and parallel was 31.4, does that indicate that series is more capatible with resistor 100 and series is with resisotr 47?

When they ask you to compare two resistances they mean for you to state which resistance is greater.

I don't quite understand what this means, show the experimental and theoretical calcs. for the resistance of the series/parallel. If i have the measured series as 146.7 and 31.7 as parallel, and the total equivalent resistance is 47 & 100

The experimental calculation is what you got by averaging the resistances from each individual data point. The theoretical calculation comes from plugging the values of the single resistances into the formulas for series and parallel resistance.

for the parallel series, adding the r's will be 1/r? also determining whether or not ohm's law is obeyed in this experiement is where the graph is showing a growth trend?

xswtxoj said:
for the parallel series, adding the r's will be 1/r?

Weren't you taught a formula for adding resistors in parallel?

also determining whether or not ohm's law is obeyed in this experiement is where the graph is showing a growth trend?

More specifically, the voltage should grow linearly with current. Ohm's law is the equation of a line with slope R in the v-i plane.

## 1. What is the formula for determining the effective resistance of two resistors in series?

The formula for determining the effective resistance of two resistors in series is Req = R1 + R2, where R1 and R2 are the individual resistances.

## 2. How do I calculate the total resistance if I have more than two resistors in series?

To calculate the total resistance of multiple resistors in series, simply add all of the individual resistances together. The formula for this is Req = R1 + R2 + R3 + ... + Rn, where n is the number of resistors in the series.

## 3. Can I use the same formula for resistors in parallel to determine the effective resistance in a series circuit?

No, the formula for determining the effective resistance of resistors in parallel is different from that of resistors in series. In a parallel circuit, the effective resistance decreases as more resistors are added, while in a series circuit, the effective resistance increases.

## 4. If the resistors in series have different values, how do I calculate the effective resistance?

To calculate the effective resistance of resistors in series with different values, you can use the formula Req = R1 + R2 + R3 + ... + Rn, where R1, R2, etc. are the individual resistances. Alternatively, you can use the formula Req = (R1 * R2 * R3 * ... * Rn) / (R1 + R2 + R3 + ... + Rn), which takes into account the different values of the resistors.

## 5. How does the effective resistance in a series circuit affect the flow of current?

The effective resistance in a series circuit is directly proportional to the flow of current. This means that as the effective resistance increases, the flow of current decreases, and vice versa. This relationship is described by Ohm's Law: I = V/R, where I is the current, V is the voltage, and R is the resistance.

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