Valves of the Heart. The heart functions by pumping blood both to the lungs and to the systems of the body. To prevent blood from flowing backwards or âregurgitatingâ back into the heart, a system of one-way valves are present in the heart.
An electric circuit is a path in which electrons from a voltage or current source flow. Electric current flows in a closed path called an electric circuit. The point where those electrons enter an electrical circuit is called the source of electrons.
I'm not sure what was meant by whoever told you that the direction of the electrons is generally unknown. On average, the electrons move from negative to positive electrical potential in a DC circuit, as you said. Perhaps what they meant is that if you pick a particular electron and look at its velocity, it could be in any random direction. That's because the electrons are constantly bouncing off of each other and the atoms in the wire, causing the energy losses known as electrical resistance (also called Ohmic losses). So at any given moment, the actual direction of an individual electron is random.