Answer :
Final answer:
When three bulbs of 25 W, 60 W, and 100 W, all rated for 220 V, are connected in series to a 220 V supply, each will glow less brightly than at its rated power due to increased total resistance and thus reduced current, with varying brightness levels reflecting their different resistances.
Explanation:
If three bulbs of 25 W, 60 W, and 100 W, all rated for 220 V, are connected in series across a 220 V supply, the electrical current flowing through each bulb will be determined by the total resistance of the circuit. Since these bulbs are connected in series, the total resistance increases, and the current through the circuit decreases compared to if the bulbs were connected individually to the power supply. The power dissipated by each bulb will be different from its rated power because the voltage drop across each bulb will also differ. This is because the resistance of each bulb is different, leading to varying voltage drops that do not necessarily add up to the total supply voltage when in series. This setup will cause each bulb to glow less brightly than it would at its rated power, and the difference in glow intensity among the bulbs will also highlight their differing resistances.