Home › Ask the Teacher Forums › Fundamentals › voltage drop quiz › Reply To: voltage drop quiz
![](https://mastersamuraitech.com/wp-content/uploads/2016/01/Susan-Brown_avatar-80x80.jpeg)
Here’s more for you to mull over.
Voltage (without the “drop”) can just be a difference in charge that is present, but no current is flowing. For example, the voltage measured at an outlet, or voltage measured across an open switch (or a load that has failed in an open state).
Voltage drop is voltage that exists in a particular circumstance: when current is flowing through a load. When this is happening, there will be measurable voltage when measuring from one side of the load to the other.
By contrast, when you measure across a closed switch, you will measure zero voltage, even if current is flowing, because a switch has essentially zero resistance.