Voltage and Voltage Drop are concepts that a lot of techs struggle to nail down.
We defined in earlier units that “voltage” is basically the difference in electrical charge between two points.
As for voltage drop, here’s what we currently have in Unit 8 of Basic Electricity. Let me know where you still have trouble defining it – we’re always looking for ways that might click better with some students!
Here’s the key concept with voltage drop: A voltage drop across a load is produced when current flows through that load.
When we talk about voltage drop, we’re always talking about a specific load that has current flowing thorough it. That’s why it makes no sense to talk about the voltage drop at a wall outlet that we’re checking with our meter, for example, because there’s no current flow and no load (the meter doesn’t count as a load– a good meter should never load the circuit enough to make a difference).
In the course of doing its work, a load will have a voltage drop across it that is proportional to the resistance of that load…. (then we go on to show the Ohm’s Law equations that describe this, including how to calculate V drop across a load versus in the whole circuit.)