# Liquid Metal Under Applied Voltage

by ApplePi314
Tags: applied, liquid, metal, voltage
 P: 5 Hi guys! I have a question regarding liquid metals. Suppose you had a droplet of liquid metal in empty space. Take the droplet and connect it to a DC source. What happens if the voltage of the DC source exceeds the surface tension of the liquid metal droplet? Would the droplet split in two? Would it expand? I'm really curious and appreciate anyone taking the time to answer. Thanks!
 Mentor P: 3,954 You mean that you connect one side of the voltage source to one side of the droplet, and the other side of the voltage source to the to other side of the droplet? Liquid metal conducts (google for "mercury switch") so you've just created a short circuit. Whatever is the weakest link in the circuit will burn, explode, boil, or do something else exciting.
 P: 5 Hey Nugatory! thanks for the reply. I guess a better example would be two droplets, one connected to the positive terminal of the DC source and the other connected to the negative terminal. I'm trying to figure out how the droplets would respond to the applied potential (Would they split into smaller droplets or expand until the total surface tension matched the voltage? Would they boil?). Thanks again!
PF Gold
P: 1,909
Liquid Metal Under Applied Voltage

 Quote by ApplePi314 Hey Nugatory! thanks for the reply. I guess a better example would be two droplets, one connected to the positive terminal of the DC source and the other connected to the negative terminal. I'm trying to figure out how the droplets would respond to the applied potential (Would they split into smaller droplets or expand until the total surface tension matched the voltage? Would they boil?). Thanks again!

Voltage is measured in volts obviously. How could volts "match" the dimensional units used for surface tension?

Surface tension measurement are often expressed as dynes-per-centimeter, is the same as surface energy, which is often expressed as ergs per square centimeter (erg/cm2 = dyne cm/cm2 = dyne/cm. A soap film may have a surface tension of 25 dynes/cm. Mercury would be typically in the region of 480 dynes/cm.

For an excellent review of exactly how liquid metals are measured see:
Surface Tension Measurements of Liquid. Metals by the
Quasi-Containerless Pendant Drop Method
Kin F. Man
Jet Propulsion Laboratory
California Institute of Technology
mN-m-1
http://trs-new.jpl.nasa.gov/dspace/b.../1/99-1764.pdf