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1)WHAT ARE THE ADVANTAGES OF CONNECTING ELECTRICAL DEVICES IN PARALLEL WITH THE BATTERY INSTEAD OF CONNECTING THEM IN SERIES? 2)WHY DOES THE CORD OF AN ELECTRIC HEATER NOT GLOW WHILE THE HEATING ELEMENT DOES? 3)WHAT DETERMINES THE RATE AT WHICH ENERGY IS DELIVERED BY A CURRENT?

The arrangement of lights and various other electrical appliances in parallel circuits is used in domestic wiring because of the following advantages:

1.    In parallel circuits, if one electrical appliance stops working due to some defect,then all other appliances keep working normally. For example, if a number of bulbs are connected in parallel circuits and one bulb gets fused (or blows out), then all the remaining bulbs will keep glowing.

2.      In parallel circuits, each electrical appliance has its own switch due to which it can be turned on or turned off independently, without affecting other appliances. For example, all the bulbs joined in parallel circuits in a house have separate switches due to which we can switch on  or switch off any bulb as required, without affecting other bulbs in the house.

3.    In parallel circuits, each electrical appliance gets the same voltage (220 V ) as that of the power supply line. Due to this, all the appliances will work properly. For example, all the bulbs connected in parallel circuits get the same voltage of 220 volts of the power supply line and hence glow very brightly.

4.  In the parallel connection of electrical appliances , the overall resistance of the household circuit is reduced due to which the current from the power supply is high. Every appliance can, therefore, draw the required amount of current. For example, in parallel circuits ,even the high power rating appliances like electric irons, water heaters and air conditioners, etc, can draw the high current needed for their proper functioning.

The heating element (or coil ) of an electric heater made of nichrome glows because it becomes red-hot due to the large amount of heat produced on passing current (because of its high resistance),but the cord or connecting cable of the electric heater made of copper does not glow because negligible heat is produced in it by passsing current (because of its extremely low resistance).