They are hard to see because they are so small and move so fast, however, they are green. This can be converted to miles per hour, or furlongs per fortnight if so desired, but volts are nice and tidy. There are so many in a pound, it is inconvenient to weight them. This is just how hard the peas hit. Same principle as getting hit with a water hose.
Electrical power is measured in watts.
This is defined as work. This is resistance and it is measured in ohms. Heat deteriorates insulation. A pack of peas will cram itself into a pipe until the resistance to movement they create by rubbing uses up all their available speed. Volts divided by Ohms.