Question

What did you include in your response? Check all that apply.

1) The bulb will not light.
2) This is a short circuit.
3) The branch without the bulb has almost no resistance, so all the current will flow through it instead of through the bulb.

Answer 1

When too many bulbs in a holiday light string burn out, the shunts open due to an excessive increase in current caused by the reduced resistance, leading to a high power dissipation as heat, which can damage the shunts.

Step-by-step explanation:

Strings of miniature holiday lights often use a device called a shunt that allows current to bypass a bulb when it burns out, creating a path around the open circuit. When too many bulbs burn out, the shunts also open because the current becomes too high. With each bulb that burns out, the resistance in the circuit decreases (since they are connected in series), leading to an increase in current according to Ohm's Law (I = V/R). This excess current increases further with additional bulbs burning out, eventually becoming too high for the shunt to handle, causing it to open and the light string to stop functioning.

Incandescent light bulbs work as resistors that emit light when heated by the current. If high current situations occur, like in a short circuit, the power dissipation increases dramatically, potentially damaging the circuit components, including the shunts. This is due to a high power dissipation which is calculated by P = I²r, indicating that as the current increases, the power dissipated as heat also increases, which can lead to the failure of shunts.