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# Any know how to tell if a graph has Exponential Decay?

Found 16th Apr 2011
As title really, how do you know if a graph/chart has exponential decay?

How do you work this out?
Plot it on log graph paper and it should be a straight line

The way i read it is that the drop in results against the increase of X makes it exponential decay?

Or am i missing the point.

hughwp

Plot it on log graph paper and it should be a straight line

What happens if the results decay slightly when on log paper? (which they do)

choc1969

http://serc.carleton.edu/introgeo/teachingwdata/Graphsexponential.html

Thanks, have checked out that site and no wiser lol

Edited by: "mds1256" 16th Apr 2011
If the quantity decreases by one half in a characteristic time, then you will get a graph that curves down rapidly to begin with and then tails off.
I will look for an example.

like this:
graph
Edited by: "chesso" 16th Apr 2011
When you say will form a straight line does that mean a straight line or.a straight diagonal line?
mds1256

When you say will form a straight line does that mean a straight line … When you say will form a straight line does that mean a straight line or.a straight diagonal line?

no, it will be a curved line as per the graphical evidence above ^^^^^

In exponential decay, the rate of change decreases over time - the rate … In exponential decay, the rate of change decreases over time - the rate of the decay becomes slower as time passes. Since the rate of change is not constant (the same) across the entire graph, these functions are not straight lines.

[image missing]

That's great thanks!
Edited by: "mds1256" 16th Apr 2011
mds1256

When you say will form a straight line does that mean a straight line … When you say will form a straight line does that mean a straight line or.a straight diagonal line?

If will be a sloped line but depends on base of logs most people will assume natural logs (2.7 odd) as it's whats mostly found in science.

Answered and closed at OP request

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