= Solution
A <Ragone plot> has <specific energy> $e_s=E/m$ on its horizontal logarithmic axis and <specific power> $p_s=P/m$ on its vertical logarithmic axis, normally in $\mathrm{Wh\,kg^{-1}}$ and $\mathrm{W\,kg^{-1}}$. The comparison must use the same <mass> convention: complete devices cannot fairly be compared with electrode-active-material values. At approximately constant delivered power, the discharge time is
$$
t_{\rm h}=\frac{e_s}{p_s},\qquad t_{\rm s}=3600\frac{e_s}{p_s}.
$$
Thus constant-time lines slope upward on the log–log plot. \b[Ordinary <capacitors> lie toward high power and low <energy>; <batteries> toward higher <energy> and lower power; <supercapacitors> bridge the two.] Technology and operating limits produce overlapping regions, not universal sharp boxes.
\Image[/past-exam-of-the-mphil-in-micro-and-nanotechnology-enterprise-course-of-the-university-of-cambridge/2019/paper-1-ragone.png]
{title=Original qualitative Ragone comparison with logarithmic axes and representative constant-discharge-time lines}
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