 |
| Rating of Electrical Appliances |
|
| Generally electrical appliances such as an electric bulb, geyser, heater, etc. are rated with power and voltage.
If a bulb is rated 100W - 250V, it means that when a bulb is lit on a 250V
supply, it consumes 100 W of electric power. This means that, 100 J of electrical energy gets converted into heat and light energy in 1 second. |
| |
| From this rating we can calculate the resistance of the filament of the appliance while it is glowing and also the current which flows through it. |
| |
 |
| |
 |
| |
| For the bulb rated as 100 W - 250 V, the resistance of its filament |
| |
 |
| |
| The resistance of the filament of a bulb is much less than this value when it is not lit because the resistance of a filament increases with the increasing temperature. |
| |
