Radioactive decay as a function of time. The vertical axis shows the number of particles (or the activity) as a percentage of the initial value; the half life T½ = ln(2) * τ, where  τ is the average life time.
<ul><li><a href="//commons.wikimedia.org/wiki/File:Series_RC_resistor_voltage.svg" title="File:Series RC resistor voltage.svg">Series_RC_resistor_voltage.svg</a>: <a href="//commons.wikimedia.org/wiki/User:Ktims" title="User:Ktims">User:Ktims</a></li>
<li>derivative work: <a href="//commons.wikimedia.org/wiki/User:Pieter_Kuiper" title="User:Pieter Kuiper">Pieter Kuiper</a> (<a href="//commons.wikimedia.org/wiki/User_talk:Pieter_Kuiper" title="User talk:Pieter Kuiper"><span class="signature-talk">talk</span></a>)</li></ul>
<ul><li><a href="//commons.wikimedia.org/wiki/File:Series_RC_resistor_voltage.svg" title="File:Series RC resistor voltage.svg">Series_RC_resistor_voltage.svg</a></li></ul>