Question

how is electrical energy expressed?

Answer 1

Electrical energy is expressed in joules, power is expressed in watts, and time is expressed in seconds.  

For example, if a 100 watt light bulb is turned on for one hour (3600 seconds), you can use the above formula to calculate how many joules of energy are being used.  

Energy = 100 watts x 3600 seconds

Energy = 360,000 joules

As you can see, the numbers will get big very quickly.  That's why some power companies will express electrical energy consumption in kilojoules.  The above number would then be 360 kilojoules. 

hope it helps

Answer 2

Electrical energy is expressed in Joules.
Electrical energy = power × time .
power in watt.
time in seconds...