A student connects six identical cells, each with an electromotive force (emf) of 1.5 V, in series as shown in the diagram. Two of the cells are connected with reversed polarity.
What is the net potential difference across the terminals A and B?
9.0 V9.0\text{ V}9.0 V
6.0 V6.0\text{ V}6.0 V
3.0 V3.0\text{ V}3.0 V
1.5 V1.5\text{ V}1.5 V