= Solution
<specific energy> is usable stored <energy> divided by device <mass>, commonly in Wh/kg; <specific power> is deliverable <power> per the same <mass>, in W/kg. The definition must specify whether packaging and inactive components count, and the discharge conditions must be comparable. On a <Ragone plot> with <energy> horizontal and <power> vertical, ordinary <capacitors> occupy high-power/low-energy territory, <batteries> tend toward higher <energy> and lower <power>, and <supercapacitors> bridge and overlap the two. These are broad regions rather than universal measured boundaries.
\b[High <specific energy> means long operation for a given <mass>; high <specific power> means rapid delivery.] Their ratio is a characteristic duration: $t_{\rm h}=e_s/p_s$ when the preceding units are used, or $t_{\rm s}=3600e_s/p_s$. The diagonal lines in the sketch keep that unit conversion explicit. A cell's rated <energy> and peak pulse <power> need not be available simultaneously throughout discharge.
\Image[/past-exam-of-the-mphil-in-micro-and-nanotechnology-enterprise-course-of-the-university-of-cambridge/2017/paper-1-ragone.png]
{title=Qualitative storage regions and constant-duration lines on a <Ragone plot>}
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