Lab Exercise: How do I make a logarithmic curve linear?

In summary, the conversation was about an experiment where the power radiated by a light bulb filament was measured as a function of its absolute temperature. The data was then plotted and it was suggested to assume a power function and re-plot the data. The steps for finding the best value for the power function were discussed, where the slope of a trend line was used to determine the power value.
  • #1
CarbonWater
20
0

Homework Statement


In a certain experiment, the power (P) radiated by a light bulb filament was measured as a function of the filament's absolute temperature (T).

Data:
P(W)
0.45
0.95
1.8
3.5
5.6

T(K)
1000
1200
1500
1800
2000

(a) Plot the data (Done)

(b) Assume a power function and re-plot the data.

Homework Equations



Unsure.

The Attempt at a Solution



I plotted the data and it looks like a natural logarithm. I'm not sure what to do next. Raising each T value to the power of 2 straightens out the curve a bit but not completely. Is that what it means to assume a power function? If a power function is y=kx^a, how do I know which exact a to take and where do I get k from? Thanks.
 
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  • #2
Suppose P = T^n.
Then ln(P) = ln(T^n) = n*ln(T).
If you graph your data as ln(P) vs ln(T), (and the data is perfect) you will get a straight line with slope n. Imperfect data (isn't it always?), the slope of a trend line is the best value for n.
 
  • #3
Thank you. That was what my professor was looking for.
 

1. How do I make a logarithmic curve linear?

To make a logarithmic curve linear, you can take the logarithm of both the x and y values. This will transform the data into a linear form, which can then be plotted on a graph.

2. Why do I need to make a logarithmic curve linear?

Sometimes, data may follow a logarithmic relationship rather than a linear one. By transforming the data into a linear form, it becomes easier to visualize and analyze the relationship between the variables.

3. What type of data is best represented by a logarithmic curve?

Data that increases or decreases rapidly at first, then slows down or levels off, is best represented by a logarithmic curve. Examples include population growth, microbial growth, and radioactive decay.

4. How do I know if my data follows a logarithmic relationship?

You can determine if your data follows a logarithmic relationship by plotting it on a graph and observing the trend. If the data appears to increase or decrease exponentially, it is likely a logarithmic relationship. Another way to check is by taking the logarithm of both the x and y values and seeing if the resulting data is linear.

5. Are there any limitations to using a logarithmic curve to represent data?

Yes, there are some limitations to using a logarithmic curve. For example, it may not accurately represent data that follows a linear relationship or data that has a large range of values. Additionally, interpreting the relationship between variables may be more difficult when using a logarithmic curve.

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