Question

Consider first two cells in series as shown in figure the potential difference between the terminals $A$ and $C$ of the combination is

• A. $V_{A C}=\varepsilon_{1}-Ir_{1}$
• B. $V_{A C}=\varepsilon_{2}-I r_{2}$
• C. $V_{A C}=\varepsilon_{ eq }-I r_{ eq }$
• D. $V_{A C}=2 \varepsilon_{ eq }-I r_{ eq }$

Answer 1

Answer: (C)

$ V_{A C}=V(A)-V(C) =[V(A)-V(B)]+[V(B)-V(C)] =\varepsilon_{1}-I r_{1}+\varepsilon_{2}-I r_{2} $
$=\left(\varepsilon_{1}+\varepsilon_{2}\right)-I\left(r_{1}+r_{2}\right)=\varepsilon_{ eq }-I r_{ eq } $