What does potential drop across a resistor actually mean?

[jaredvert]

When one says there is a "potential drop" across the resistor, they do not mean the actual voltage has gone down right? They just mean the current has? But then I question that because since the current goes down then the voltage has to as well? I am fuzzy on this subject, can you explain? Why is there a potential drop? Just because the current goes down?

 

[danshawen]

Voltage "goes down"

Yes, they do.

For example, consider a single battery, and a single resistor in parallel. The voltage at the + side of the battery is +V, and the voltage at the - side of the battery is zero volts. The difference (potential drop) would be V.

For two equal value resistors in series with the same battery half of the voltage drops across each resistor. For unequal resistances in series, you have a voltage divider. The current through both is the same and V = IR, so what do you think will happen?