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Exponentials and Logarithms · Already know this?

Ten questions, one verdict per topic

Answer all ten without looking anything up. The result tells you, topic by topic, which lessons you may skip and which you should read.

Already know this?

Ten questions. The result tells you which lessons you may skip.

1

A ball dropped from \(1.25\,\text{m}\) keeps \(64\,\%\) of its height at every bounce. How high does it rise after the second bounce?

2

What is the slope of the curve \(y = e^x\) at \(x = 1\)?

3

A quantity decays as \(y_0e^{-t/\tau}\). What fraction is left after one time constant?

4

A capacitor discharges with \(\tau = 2\,\text{s}\). Its half-life is about

5

On the graph of \(y_0e^{-t/\tau}\), where does the tangent at \(t = 0\) meet the time axis?

6

A capacitor charges through a resistor with \(\tau = 1\,\text{s}\). What fraction of its final charge does it hold after \(3\,\text{s}\)?

7

Which of these equals \(\ln 6\)?

8

A sample falls to one tenth of its activity. How many time constants has that taken? Take \(\ln 10 = 2.3\).

9

Two identical loudspeakers each give \(80\,\text{dB}\) at a point. Together they give

10

To read a decay constant from measured counts \(A\) at times \(t\), which graph should be a straight line?