Question

Which of the two, Kilowatt hour or electron volt is a bigger unit of energy and by what factor?

Answer 1

Kilowatt hour is bigger unit of energy.

Let's try to understand ,
 kilowatt hour = 1000watt hour 
                      = 100 × 60 × 60 watt sec 
                      = 3.6 × 10⁶ J [∵ watt = j/s so, watt.sec = j]
hence, kilowatt hour = 3.6 × 10⁶ J 

now, electron volt ,eV = 1.6 × 10⁻¹⁹ C.volt 
                                   = 1.6 × 10⁻¹⁹ J [ ∵ 1volt = 1J/C so, C.volt = J ]
hence, eV = 1.6 × 10⁻¹⁹ J 

now what you observed,
   kilowatt hour is bigger than electron volt. and kilowatt hour is 3.6 × 10⁶/1.6 × 10⁻¹⁹ = 2.25 × 10²⁵ times bigger than electron volt

Answer 2

Energy is the capacity to do work.

Energy is measured in same unit as work.

Si unit of energy is joule and C.G.S unit is erg.

Bigger unit of Energies are Kilowatt hour

1kWh=1 kwatt x 1 hour

=1000 joule/sec  x 3600 s

1kwH=3.6 x 10⁶ joules

where as the the energy of atomic particles is very small and is measured in electron volt.

1ev=1.6 x 10⁻¹⁹ j

1electron volt is the energy gained by an electron accelerated in an electric field by a p.d of 1 volt.

1kwh/1eV=3.6 x 10⁶ J/1.6 x 10⁻¹⁹ J=2.25 x 10²⁵

so 1 KwH is 2.25 x 10²⁵ times bigger than 1 electron volt.