If i have a=exp x, and i know that my uncertainty in a is 3% ( at all

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The discussion focuses on calculating the uncertainty in the variable x when given the equation a = exp(x) and a known uncertainty of 3% in a at a point where a = 2. The correct approach involves using error propagation, specifically the relationship x = ln(a), which leads to the derivative dx = da/a. The absolute uncertainty in x is determined to be equal to the percentage uncertainty in a, confirming that the uncertainty in x is 1% when a = 2 and x is approximately 3mm.

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if i have a=exp x, and i know that my uncertainty in a is 3% ( at all points). At a point where a=2, how do we calculate the uncdrtainty in x.

is the absolute value = (3% of ln 2)/ln 2, which equals 0.03mm, which equals 1% (if x is 3mm)

thanks
 
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x cannot have units of mm in that equation, and a=2 does not correspond to x=3.

Use error propagation - write the expression as x=ln(a), the derivative with respect to a is easy to find then.
The formula looks good, but the result has the problem mentioned above.
 
so dx = da/a?

so the absolute uncertainty in x is equal to the percentage uncetainty in a?
 

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