Power

To determine the total power drawn by identical light bulbs connected in series, let's consider the following:

• Each bulb has a power rating of , which means when it is connected individually to the supply voltage, it would draw power .
• When bulbs are connected in series, the total voltage is divided among them.
• If is the total voltage of the source, each bulb will receive a voltage of because the total voltage is shared equally among the bulbs in series.
• The power drawn by each bulb when connected in series is given by the formula for power: , where is the resistance of one bulb.
• In series, the voltage across each bulb is , so the power across each bulb is:

• The total power drawn by all bulbs is:

• Since each bulb alone draws power , the expression for total power becomes:

Therefore, the total power drawn by the bulbs when connected in series is .