Two batteries that are identical each have e.m.f. $6.0\,\text{V}$ and internal resistance $r$. As illustrated, the batteries are linked to an external resistor with resistance $11\,\Omega$. The current through the external resistor is $0.50\,\text{A}$. What is the value of the internal resistance $r$ for each battery?
- A$1.0\,\Omega$
- B$2.0\,\Omega$
- C$4.0\,\Omega$
- D$6.5\,\Omega$