ANSWER
If a second identical lamp is connected in series, the 6-volt battery must push a charge through a total resistance of 6 Ω. The current in the circuit is then 1 Amp.
EXPLANATION
The first circuit was made of a battery and a lamp. Now, a second identical lamp - i.e. with the same resistance, is connected in series, so we have the following circuit,
The equivalent resistance of the circuit is the sum of the resistances of each lamp,
[tex]R_{eq}=R+R=3\Omega+3\Omega=6\Omega[/tex]And, by Ohm's law, the total current through the circuit is,
[tex]I=\frac{V}{R_{eq}}=\frac{6V}{6\Omega}=1A[/tex]Hence, the total resistance is 6 Ω and the current in the circuit is 1 Amp.
