Question

Which one of the following is not a unit of energy ?
1. Newton metre
2. kCal
3. Watt
4. Watt hours

Answer 1

Correct Answer - Option 3 : Watt

Concept:

Energy

• Energy is the capacity to do work. 
• It is neither created nor destroyed. 

Units of Energy

Joule:

• Joule is the SI unit of Energy. 

Electron volt: 

• It is the amount of energy required to move an electron from one point to another across the potential difference of 1 volt. 
• 1 electron volt = 1.602 × 10-19 Joule

Erg:

• The unit of energy expressed in centimeter-gram-second (cgs) is called erg.
• 1 erg = 10-7 J

Calorie:

• The amount of energy required to raise the temperature of 1 gram of water by 1°C or 1 Kelvin is called Calorie.
• 1 calore = 4.186 J

KwH: 

• This is a commercial unit of energy. It is the energy consumed when a device with power rating 1 Kilowatt is used for 1 hour. 

1 KwH = 3.6 × 10 6 J

Newton-meter

• Work done is said to be 1 joule, when a force of one newton actually moves a body through a distance of one meter in the direction of applied force.

Watt

• It is the work done in unit time.
• Watt is the unit of power.