A, the current of the series circuit is equal everywhere, as shown in the figure, two bulbs are connected in series. After closing the switch, it is found that L 1 emits light, while L 2 does not, indicating that the circuit is a path; So, A is wrong;

B, according to P=I 2 R, the resistance of bulb L 1 is much greater than that of L 2, so B is wrong;

C, because the rated voltage of the bulb is the same, and the resistance of the bulb L 1 is much larger than that of L 2, it can be seen from P= U 2 R that the rated power with smaller resistance is large, that is, the rated power of L 2 is relatively large; Therefore, C is correct;

D, from U=IR, the actual voltage of L 1 is greater than the actual voltage at both ends of L 2; So, d is wrong.

So choose C.