# At what resistance do I not see a voltage drop across a resistor?

If I have a circuit like this and measure the voltage drop across the resistor I get a value, regardless of what resistor I use:

However, if I stick a piece of wood in there instead of the resistor I get nothing. My intuition says there must be some resistance value between wood and conductor where the voltmeter switches from reading the voltage source to reading zero. Is that how this works? Is there some high resistance value where the voltmeter reads a fraction of the source voltage? Is my understanding of electronics terribly wrong?

EDIT: I suspect the answer has to do with current and the voltmeter not being an ideal, infinite resistance machine, but I can't get from there to the answer.

• as long as current exists, so does a voltage drop. Mar 4, 2014 at 2:11
• Usually we measure a voltage drop across a component. Mar 4, 2014 at 2:21
• In your schematic, you've got an apparent voltmeter connected like an ammeter. Since an ideal voltmeter is an open circuit, there is no current through the resistor (i.e., you don't actually have a circuit) and thus, there is no voltage across it. Said voltmeter should read the source voltage for any finite resistance. If you want to measure the voltage across the resistor, replace the voltmeter with a wire and place the voltmeter in parallel with the resistor. Mar 4, 2014 at 2:31
• Sorry if I was unclear, that was exactly my question - "Said voltmeter should read the source voltage for any finite resistance". What is finite? Isn't an insulator still a large, but ultimately finite resistance?
– Nate
Mar 4, 2014 at 2:38