How me diagnose a DC electrical problem

[sleddriver]

Originally Posted By: Merkava_4
Originally Posted By: sleddriver
Yes, DC electron current flows from neg to pos.

If electrons flow from negative to positive, then why is ground always on the negative side ?

Electron current flow vs. potential difference. The later being taken from high PD with respect to ground (low).

Current and voltage are inter-related but not the same thing. The former is like a volume or CFM, while the later is more related to pressure or potential. How much force is behind the flow?

Voltage x Current = Power in watts.

The negative side has been tied to ground (formerly Earth) by convention for a long time. Earth being a zero potential and everything above "Earth" having a higher potential, thus "+12V above ground" or "+12V with respect to ground".

 

[supton]

Originally Posted By: Merkava_4
Originally Posted By: sleddriver
Yes, DC electron current flows from neg to pos.


If electrons flow from negative to positive, then why is ground always on the negative side ?



Convention. In reality GND is often just were we measure voltages relative to. Many of the electronic designs I work on have positive and negative voltages, with GND "in the middle".

Back in the old days there were positive GND vehicles. I don't recall why the change, just that it did change.

 

[Gokhan]

Think of the voltage as pressure, plus being higher and minus being lower. Think of the current as water flow.

Therefore, current (water) flows from positive (higher pressure) to negative (lower pressure). As it does so, it loses its energy (voltage).

The only exception is the battery (water pump). Inside the battery (water pump), the current (water) flows from negative (low pressure) to positive (high pressure) because that's where the current (water) gains its energy (voltage).