Power rating and energy consumption

You should be able to :
1. compare power rating and energy consumption of various electrical appliances.
2. compare various electrical appliances in term of efficient use of energy.
3. suggest ways of increasing energy efficiency.

Notes:

Most electrical appliances indicate their voltage and power ratings on their label.
The label "120V 1200W" means that the hair dryer will consumed 1200J of electrical energy every second if it is connected to the 12o V main supply.

Electrical energy consumed , E = power rating, P x Time of usage, t

The energy consumption of an electrical appliance depends on the power rating and time of usage.

• the larger the power rating in the electrical appliance, the more energy is used in every second.

• the longer the usage time, the more electrical energy is consumed.

The efficiency of an electrical appliance is determined by the ratio of used output to the input energy.

Efficiency = (Useful power output / power input ) x 100%


source: http://science.howstuffworks.com/earth/green-technology/sustainable/home/cfl-bulb.htm

A tungsten-filament light bulb uses electrical energy to heat up the filament to a hight temperature until the tungsten atoms are excited before they emit a useful amount of visible light. However, most of the energy is lost to the surrounding in form of heat energy.

The fluorescent bulb activates phosphor coating inside the lamp gives off light whrn it is exposed to ultraviolet radiation. the bulb doesn't use heat to create light, which is more energy efficient.



Ways to reduce energy wastage:

i) Scheduled maintenance enable an electrical appliances to function efficiency in ensuring the efficiency of electrical energy usage.
ii) Buy high energy product.