ELECTRICAL ENERGY AND POWER

 

ELECTRICAL ENERGY AND POWER

Electrical Energy

Work is done when electricity flows from one point to another of different potential. If Q coulombs of electricity flows between the two points whose differences in potential is V volts, then the work done (W) is given by

W = QV (joules).

The quantity of electricity Q coulombs is given by Q = It. Where I is the current in amperes and t is the time of flow of current in seconds.  W = QV = IVt = I2Rt.

Electrical power

Electric power is the amount of electrical work done per second.

Power =  =  = IV = I2R =  (watts)

Electrical appliances usually have some markings on them indicating their rating in watts and in volts. A mark of ’60 watts , 220V’ means that the appliance consumes a power of 60 watts (or  energy of 60 joules per second) when connected to a circuit which maintains a potential difference of 220 V across it. This implies that the current required to run the appliance can be obtained from the relation. P= IV; 60 W = I x 220 V; I = 60 / 220 = 0.2727 A.

Heating effect of an electric current and its application

When electric current flows through a conductor the resistance of the conductor changes electrical energy into heat energy just friction changes mechanical energy into heat. It is this heating effect of an electric current that is utilized in such devices as electric pressing iron, electric toaster, electric coil, hair dryer and incandescent lamps.

When electric power is converted into heat, the greater the value of current the greater the heat generated. The heat generated is proportional to the square of the current, the resistance and the time during which the current flows, according to the relation:

H = I2Rt.

Conversion of Electrical Energy into other forms of Energy.

i. Conversion of an electrical energy to mechanical energy : this conversion is made possible through the action of electric motors. E.g movement of electric blades of electric fans and in washing machine.

ii. to Heat energy: e.g electric kettle, electric iron, immersion heater (boiling ring)

iii. Light energy: e.g in the glow of filament lamps or bulbs.

iv. Sound energy: e.g in the telephone ear-piece, in music from record players.

 

Comments

Post a Comment

Popular posts from this blog

POST HARVESTING PROCESSES

CHAPTER TWELVES POST HARVESTING PROCESSES 12.1             CONCEPTS AND PHILOSPHY OF POST HARVEST TECHNOLOGY Post-harvest fisheries entails all steps, process and or activities immediately after catch handling and transportation processing and distribution of fish and fishery product where if control is not applied post-harvest losses will occur.         Post –harvest fish losses are a major concern and occur in most fish distribution chains throughout the world. Not only do losses constitute lost income to fishers, processors and traders, they also contribute food insecurity i.e a loss of fish means less fish available for the consumer. POST HARVEST PROCESSES:         Fish are highly perishable. A central concern of fish processing is to prevent fish from deteriorating . Causatic factors of fish spoilage 1. High moisture content.   ...
Read more

NICOM SAT 1

TOPIC: - NICOM-SAT 1    INSTRUCTIONAL MATERIALS: -         Satellite dish REFERENCES BOOK: -     1.      FARINDE O. E e tal, ESSENTIAL PHYSICS FOR SSS, Tonad Publishing Limited. 2.      M. W. ANYAKOHA (2011), NEW SCHOOL PHYSICS FOR SENIOR SECONDARY SCHOOLS, Africana first publishers.    3.      INTERNET PREVIOUS KNOWLEDGE: -     Students have been taught Niger-sat 1 INSTRUCTIONAL OBJECTIVES: - At the end of the lesson students should be able to: - 1.        Explain the concept of NICOM-SAT 1 2.        State the features of NICOM-SAT 1 3.        Uses of NICOM-SAT 1 CONTENT: - NICOM- SAT 1 NigComSat-1 is a Nigerian Communication Satellite. It was launched on 14 may, 2007 in China by China Great Wall Industry...
Read more

FISH SEED PRODUCTION

CHAPTER THIRTEEN FISH SEED PRODUCTION BROOD STOCK SELECTION             Brood stock means a group of sexually mature individuals of a culture species that is kept separate for  breeding purpose. 13.1     DIFFERENCES  BETWEEN MALE  AND FEMALE SEXUALLY MATURED FISHES             Male and female breeders may be easily differentiated by the shape of the body and the relative position of genital papilla. In females, the body is plump and the genital opening is situated above the genital papilla. In males, the body is slender and the genital opening is found behind the genital papilla. External signs of the brood stock A male brood stock will release milt under a slight abdominal pressure: Its belly is not blown up but rather slim; it sometimes has callosities on the head. A female brood stock has a well-rounded and soft  or semi...
Read more