We know that in a series circuit the total voltage is equal to the voltage drop in each component; we also know that the voltage drop in each component is equal to:
[tex]V=IR[/tex]Furthermore, in a series circuit the current in each component is the same.
Let R be the resistance on each lamp, since the current is the same in each of them and they have the same resistance, we have:
[tex]\begin{gathered} V_1+V_2+V_3=V_T \\ \text{ Since all the voltage drops are the same we have:} \\ 3V=6 \\ V=\frac{6}{3} \\ V=2 \end{gathered}[/tex]Therefore, the voltage drop on each lamp is 2 V
