There are three cells with e.m.f.s $V_1$, $V_2$ and $V_3$, each with negligible internal resistance. As illustrated, these cells are linked to three resistors of resistance $R_1$, $R_2$ and $R_3$. The current flowing in the circuit is $I$. Which equation is correct?
- A$V_1 + V_2 + V_3 = I(R_1 + R_2 + R_3)$
- B$V_1 + V_2 - V_3 = I(R_1 + R_2 + R_3)$
- C$V_1 - V_2 + V_3 = I(R_1 + R_2 + R_3)$
- D$V_1 - V_2 - V_3 = I(R_1 + R_2 + R_3)$