Question

Some strings of holiday lights are wired in series to save wiring costs. An old version utilized bulbs that break the electrical connection, like an open switch, when they burn out. If one such bulb burns out, what happens to the others? If such a string operates on 120 V and has 40 identical bulbs, what is the normal operating voltage of each? Newer versions use bulbs that short circuit, like a closed switch, when they burn out. If one such bulb burns out, what happens to the others? If such a string operates on 120 V and has 39 remaining identical bulbs, what is then the operating voltage of each?

a) Old version: Others stay lit; Normal voltage: 120 V / 40.

b) Old version: Others go out; Normal voltage: 120 V / 40.

c) New version: Others stay lit; New voltage: 120 V / 39.

d) New version: Others go out; New voltage: 120 V / 39.

Answer 1

In the old version, the others go out; normal voltage: 3 V per bulb. In the newer version, the others stay lit; new voltage: 3.08 V per bulb.

Step-by-step explanation:

In the old version of holiday lights wired in series, when one bulb burns out and breaks the electrical connection, the others also go out because the circuit is broken. The normal operating voltage of each bulb in this case would be 120 V / 40, which is 3 V per bulb.

In the newer version with bulbs that short circuit when they burn out, if one bulb burns out, the others stay lit because the circuit remains closed. The operating voltage of each bulb in this case would be 120 V / 39, which is approximately 3.08 V per bulb.