How many 120-volt light bulbs should be connected in series across a 600-volt electric line?

To determine how many 120-volt light bulbs can be safely connected in series across a 600-volt electric line, you have to consider the total voltage that a series connection of the bulbs will handle.

When bulbs are connected in series, their voltages add up. Therefore, if each bulb is rated for 120 volts, connecting multiple bulbs in series means that their individual voltage ratings accumulate.

Calculating the number of bulbs that can be connected involves dividing the total voltage of the system by the voltage rating of each bulb. In this case, take the 600 volts of the electric line and divide it by the 120 volts of each bulb:

600 volts ÷ 120 volts per bulb = 5 bulbs.

However, option C states 3 bulbs, which would not utilize the full capacity of the 600-volt line, as this would equate to only 360 volts (3 bulbs x 120 volts = 360 volts).

In conclusion, realizing that light bulbs in series increase the total voltage handled, to safely match the provided voltage without exceeding it, the correct amount of bulbs to connect should be 5. Since that option isn't provided, one must acknowledge that the closest option is necessary for practical concerns,