# Light Year Long Confusion

The main question stems from the answer for this one:

If I have a light year long rod and push it on one end, how long would it take for the other end to move?

Main Question:

If I had 2, light-year long conductive rods, with a voltmeter attached at the ends then applied a voltage to it, how long would it take for the voltmeter to read the voltage?

Resources/tutorials/wiki pages please for this as well. Thanks!

Note by Charles White
1 year, 10 months ago

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For the 1st question, the answer is around 50000 years. When you push one end of the rod, the molecules in the rod push on molecules further up the rod until the push reaches the end. The push propagates through the rod at the speed of sound which (assuming it's a steel rod) is about 6000m/s.

- 1 year, 10 months ago