If a three light circuit is connected in series with two 6V batteries, and the three lights are identical, the voltage across each of the lights is 12V divided by 3, or 4V.
It depends upon the connection of the resistors, if the resistors are connected in parallel then the voltage is same where as in case of resistors connected in series the voltage is different across different resistors.
If you keep all of them in series, then each component in your circuit will have more voltage across it and more current through it, and will dissipate more power (heat). If you keep all of the batteries in parallel, then they must all be rated for the same voltage. Nothing about the circuit's performance will change, but it'll be able to operate longer before the batteries die.
If you are asking how a voltmeter should be connected in a circuit, then the answer is that it should be connected in parallel with the device across which you want to determine the voltage. This applies whether the circuit is d.c. or a.c.
Without specifics (are all the batteries end to end or are some loads between batteries, are all the loads the same resistive, capacitive or inductive value...), the generic answer is: the sum of supplied voltages must equal the sum of voltage drops across the loads.
When two identical 3v batteries are connected in series with the negative terminal of one of them in contact with the positive terminal of the other the total voltage of the combination is 6v.
9 volts.
36 volts
36 volts
The batteries can be connected in parallel or in series. In parallel, good batteries of the same voltage will have a total voltage across them equal to the voltage across one of them. Those batteries in series will have a total voltage equal to the sum of the voltage of each of the batteries.
9 Volts. By connecting this way you increase current potential (amperage) but not voltage.
In a series circuit, the voltage is the same across all components connected in a series. This is known as the series circuit voltage.
9 volts. They are in parallel, so the voltage remains the same. More current is available however.
The source voltage.
In a parallel circuit the voltage across each component is the same.
Voltage sources provide the voltage difference across an electrical circuit, these may be batteries, generators, alternators, solar cells, etc.
To measure the voltage across a component in an electrical circuit, a voltmeter can be connected in series by placing the voltmeter in the same path as the component. This allows the voltmeter to measure the voltage drop across the component accurately.
In a series circuit, the voltage is the same across all components connected in the circuit. This is due to the conservation of energy principle, where the total voltage provided by the power source is equal to the sum of the voltage drops across each component.