The capacity of an agent to do work is known as its energy. The most important forms of energy are mechanical energy, electrical energy and thermal energy. Different units have been assigned various forms of energy. However, it must be realized that since mechanical, electrical and thermal energies are interchangeable, it is possible to assign the same unit of them.
1. Mechanical Energy. The unit of mechanical energy is newton-metre (or joule) on the M.K.S or SI system.
The work done on a body is newton-metre (or joule) if a force of one newton moves it through a distance of one metre i.e.
mechanical energy in joules = force in newton x distance in metre
2. Electrical Energy. The unit of electrical energy is watt-sec or joule and is difined as follows:
One watt-second (or joule ) energy is transferred between two point if a p.d. of 1 volt exists between them and 1 ampere current passes between them for 1 second i.e.,
electrical energy in wat second ( or joule )
= voltage in volt x current in ampere x time in second
Joule or watt-sec is a very small unit of electrical energy for partical purpose. In practice, for the measure ment of electrical energy, bigger units viz., watt-hour and kilowatt houre are used.
1 watt-hour = 1 watt x 1 hr
= 1 watt x 3600 sec = 3600 watt-sec
1 kilowatt hour (kWh) = 1 kW x 1 hr
= 1000 watt x 3600 sec
= 36 x 105 watt-sec
3. Heat. Heat is a form of energy which produces the sensation of warmth. the unit (The SI or MKS unit of thermal energy being used these days is the joule exactly as for mechanical and electrical energies. the thermal units viz., calorie, B.Th.U. and C,H,U are obsolete.) of heat is calorie, British thermal unit (B.Th.U.) and centigrade heat units (C.T.U.) on the various system.
Sometimes a bigger unit namely kolocalorie is used. A kilocalorie is the amount of heat required to raise rhe temprature of 1 kg of water through 10C i.e.,
1 kilocalorie = 1 kg x 10C = 1000 gm x 10C = 1000 calories
B.Th.U. It is the amount of heat required to raise the temperature of 1 lb of water through 10F i.e.,
1 B.Th.U = 1 lb x 10F
C.H.U. It is the amount of heat required to raise the temperature of 1 lb of water through 10C i.e.,
1 C.H.U. = 1 lb x 10C
----x----
1. Mechanical Energy. The unit of mechanical energy is newton-metre (or joule) on the M.K.S or SI system.
The work done on a body is newton-metre (or joule) if a force of one newton moves it through a distance of one metre i.e.
mechanical energy in joules = force in newton x distance in metre
2. Electrical Energy. The unit of electrical energy is watt-sec or joule and is difined as follows:
One watt-second (or joule ) energy is transferred between two point if a p.d. of 1 volt exists between them and 1 ampere current passes between them for 1 second i.e.,
electrical energy in wat second ( or joule )
= voltage in volt x current in ampere x time in second
Joule or watt-sec is a very small unit of electrical energy for partical purpose. In practice, for the measure ment of electrical energy, bigger units viz., watt-hour and kilowatt houre are used.
1 watt-hour = 1 watt x 1 hr
= 1 watt x 3600 sec = 3600 watt-sec
1 kilowatt hour (kWh) = 1 kW x 1 hr
= 1000 watt x 3600 sec
3. Heat. Heat is a form of energy which produces the sensation of warmth. the unit (The SI or MKS unit of thermal energy being used these days is the joule exactly as for mechanical and electrical energies. the thermal units viz., calorie, B.Th.U. and C,H,U are obsolete.) of heat is calorie, British thermal unit (B.Th.U.) and centigrade heat units (C.T.U.) on the various system.
Calorie . It is the among of heat required to raise the temperature of 1 gm of water through 10C i.e.,
1 calorie = 1 gm water x 10C
1 kilocalorie = 1 kg x 10C = 1000 gm x 10C = 1000 calories
B.Th.U. It is the amount of heat required to raise the temperature of 1 lb of water through 10F i.e.,
1 B.Th.U = 1 lb x 10F
C.H.U. It is the amount of heat required to raise the temperature of 1 lb of water through 10C i.e.,
1 C.H.U. = 1 lb x 10C
----x----
Comments
Post a Comment