Final answer:
In a series circuit, when one bulb burns out, all the other bulbs go out. The normal operating voltage of each bulb in a series circuit with 40 identical bulbs operating on 120 V is 3 V.
Step-by-step explanation:
In a series circuit, when one bulb burns out and breaks the electrical connection, all the other bulbs in the circuit go out. This is because in a series circuit, the current has only one path to flow through, and if that path is interrupted, the current cannot flow through the other bulbs.
In the old version of holiday lights that used bulbs that break the electrical connection when they burn out, if one bulb burns out, the others will go out. To calculate the normal operating voltage of each bulb in a series circuit with 40 identical bulbs operating on 120 V, you divide the total voltage (120 V) by the number of bulbs (40), resulting in 3 V as the normal operating voltage of each bulb.
In newer versions of holiday lights that use bulbs that short circuit when they burn out, if one bulb burns out, the others will remain lit. In a series circuit with 39 remaining identical bulbs operating on 120 V, the operating voltage of each bulb will still be 3 V.