# Overview Isolates voltage of subset of series circuit $ v_k=\frac{R_k}{R_\text{series}}\,v $ # Example > Given resistors of 5, 10, 15, and 20 Ω and a 100 V source, how is voltage divided? > > $R_\text{series}= 5+10+15+20=50\,\Omega$ > > $v_5=\frac{5}{50}\left(100\right)=10\,\text{V}$ > > $v_{10}=\frac{10}{50}\left(100\right)=20\,\text{V}$ > > $v_{15}=\frac{15}{50}\left(100\right)=30\,\text{V}$ > > $v_{20}=\frac{20}{50}\left(100\right)=40\,\text{V}$