Here, we are given emf \((E)\) as \(10V,\) Resistance \((r)\) as \(3\Omega \) and current \(I\) is \(0.5A.\)
\(E=10\text V\)
\(r=3\Omega \)
\(I=0.5\text A\)
Let the unknown resistance be \(R\Omega \) .
Using Ohm's law,
\(V=\mathit{IR}\)
\(E=I(R+r)\)
\(10=\left(0.5\right)\times (3+R)\)
\(\frac{10}{0.5}=3+R\)
\(20=R+3\)
\(R=17\Omega .\)
Hence, the resistance of the resistor will be \(17\Omega \) .
To verify the voltage of the battery,
\(V=\mathit{IR}\)
\(V=0.5\times 17\)
\(V=8.5\text V\)
Hence the voltage of the battery is \(8.5\text V\) .