![Analogy with water](https://static.wixstatic.com/media/7768b9_03dfb560dcde414e817b8ee4fb2ddbea~mv2.png/v1/fill/w_49,h_28,al_c,q_85,usm_0.66_1.00_0.01,blur_2,enc_auto/7768b9_03dfb560dcde414e817b8ee4fb2ddbea~mv2.png)
But before we look at that electric system, let's have a look on an hydraulic one:
![Quantity, Height and hydraulic Power](https://static.wixstatic.com/media/7768b9_fbc2cbcd699741868c521aaba61bb44f~mv2.png/v1/fill/w_49,h_28,al_c,q_85,usm_0.66_1.00_0.01,blur_2,enc_auto/7768b9_fbc2cbcd699741868c521aaba61bb44f~mv2.png)
The water is pumped up to a certrain height called h. The quantity that flows each second is called Q. Q and h define the power P of these hydraulic wheels.
![Calculation example: Electric Power](https://static.wixstatic.com/media/7768b9_7acf4063c8a746b1854dc2f6d8db0c6c~mv2.png/v1/fill/w_49,h_28,al_c,q_85,usm_0.66_1.00_0.01,blur_2,enc_auto/7768b9_7acf4063c8a746b1854dc2f6d8db0c6c~mv2.png)
This way, we can calculate the power that is put into the circuit up and runs the motor.
![Analogy with water](https://static.wixstatic.com/media/7768b9_03dfb560dcde414e817b8ee4fb2ddbea~mv2.png/v1/fill/w_49,h_28,al_c,q_85,usm_0.66_1.00_0.01,blur_2,enc_auto/7768b9_03dfb560dcde414e817b8ee4fb2ddbea~mv2.png)
But before we look at that electric system, let's have a look on an hydraulic one:
The images and descriptions of the circuit on this page are public domain.
You may download it, copy it, modify it, distribute it, even if you do not cite the source.
Nevertheless, you might want to cite correctly:
Title=Digital Circuit 03 OR-gate
Author=Benedikt Sessler
Date=25.Sept 2020
Link=https://www.cirnavsys.com/courses/basics-01-current-voltage-and-electric-power