Two sets A and B each of four bulbs are glowing in two separate rooms. When one of the bulbs in set A is fused, the other three bulbs also cease to glow. But in set B, when one bulb fuses, the other bulbs continue to glow.

(i) Explain the difference in the two sets,

(ii) Which set of arrangement is preferred in housing circuit and why?

(i) In set A, the bulbs are in series connection. None of the bulb can be operated independently and thus when one bulb fuses the other two bulbs also ceases to glow. In set B, the bulbs are in parallel connection. Hence, when one of the bulbs fuses, the other bulbs continue to glow. Therefore, each bulb operates independently.

(ii) In housing arrangement, parallel connection is preferred. Each appliance has a separate fuse. Therefore, if due to some fault, the fuse of one appliance burns, it does not affect the operation of the other appliances.