Figure below shows three bulbs A, B and C each of rating 100 W, 220 V connected to the mains of 220 V. Answer the following:
(a) How is the bulb A connected with the mains? At what voltage does it glow?
(b) How are the bulbs B and C connected with the mains? At what voltage does the bulb B glow?
(c) How is the glow of bulbs A and C affected if bulb B gets fused?
(d) How is the glow of bulbs B and C affected if bulb A gets fused?
(a) Bulb A is connected with the mains in parallel connection. It glows at a voltage of 220 V.
(b) Bulbs B and C are connected in series with the mains.
As we know, the voltage of the source gets divided in all the appliances connected in series in ratio of their resistances.
Hence, the voltage across the two bulbs B and C will be divided equally as both have same rating.
Therefore, we get,
Hence, the bulb B will glow at a voltage of 110 V.
(c) If bulb B gets fused then there will be no effect on bulb A, as the two are connected in parallel. However, bulb C will not glow because it is connected in series with the bulb B.
(d) There is no effect on the glow of bulbs B and C if the bulb A gets fused as bulb A is connected in parallel with the bulbs B and C.