Physics (NTSE/Olympiad)  

3. Work and Energy

Energy & its Unit

Definition : Energy is the ability to do work. The amount of energy possessed by a body is equal to the amount of work it can do when its energy is released. Thus, energy is defined as the capacity of doing work. Energy is a scalar quantity and it exists in various forms.
Units of energy :The units of energy are the same as that of work. In SI system, the unit of energy is joule (J). In CGS system, the unit of energy is erg.
1 Joule = 107 ergs
Other units of energy in common use are watt-hour and kilowatt hour.
1 watt-hour = 1 watt × 1 hour
= 1 watt × 60 × 60 sec
= 3600 J
1 kilowatt-hour (kWh) = 3.6 × 106 Joule
Heat energy is usually measured in calorie or kilocalorie such that
1 calorie = 4.18 J
A very small unit of energy is electron volt(eV).
1 eV = 1.6 × 10–19 J

If you want to give information about online courses to other students, then share it with more and more on Facebook, Twitter, Google Plus. The more the shares will be, the more students will benefit. The share buttons are given below for your convenience.

NTSE Physics (Class X)

NTSE Physics (Class IX)


NTSE Physics Course (Class 9 & 10)

NTSE Chemistry Course (Class 9 & 10)

NTSE Geography Course (Class 9 & 10)

NTSE Biology Course (Class 9 & 10)

NTSE Democratic Politics Course (Class 9 & 10)

NTSE Economics Course (Class 9 & 10)

NTSE History Course (Class 9 & 10)

NTSE Mathematics Course (Class 9 & 10)