Final answer:
A series connection of voltage sources involves connecting the positive terminal of one voltage source to the negative terminal of another voltage source, creating a continuous path for the current. This configuration allows the voltage sources to add up their emfs and internal resistances to get the total values.
Step-by-step explanation:
The pair of leads connecting all the branches to the terminals of the voltage source is known as a series connection of the voltage sources. In a series connection, the positive terminal of one voltage source is connected to the negative terminal of another voltage source, creating a continuous path for the current to flow through all the branches. This configuration allows the voltage sources to add up their emfs and internal resistances to get the total values.