The Flow of Electric Charge
Narrator (Megan Watzke, CXC) Imagine you are shuffling along a carpet and reach out to touch the doorknob, and -- zap! - you get a mild shock. What's happened is the friction between your feet and the carpet has produced a large build-up of negative electric charge on your finger. This creates what is known as electric potential difference, or voltage, between your finger and the doorknob. If the electric potential difference is large enough, a sudden flow of current, called an electric discharge, will occur. While this can be in the form of a zap to your finger, it also happens on much larger scales in many different places. In fact, violent electric discharges are responsible for some of the most spectacular displays of sudden energy releases on Earth and in space.
Let's take a look at one other example that you might have come across in say, an auto body shop or at a construction site. Between a welder's tool and metal, there is a large electric voltage. This causes sparks to fly and ultimately for a strong electric current to flow. In turn, this generates a brilliant light display and enough heat to melt the metal and allow it to bond to another metallic surface.
What about electric discharge on even a larger scale? One form of electric discharge that many of us have witnessed takes place during a violent storm in the form of lightning. In massive storm clouds, the friction between large particles composed of many atoms builds up a large separation of electric charge and creates voltages approaching 100 million volts. With such a big voltage, things can get explosive, and the energy is released as a lightning bolt.
While lightning storms are certainly powerful, they are actually tame compared to the energy that can be involved in electric discharges in space. One place to look for extreme electrical flows is the spinning dense core of dead stars known as neutron stars. These objects whirl around at incredibly high speeds and also have very strong magnetic fields. This creates enormous electrical voltages – as in more than a trillion volts. When these cosmic super-generators release these giant amounts of energy, they can light up clouds that extend for trillions of miles. That's what's happening in this object known as PSR B1509-58. At the center of this image, there is a rapidly spinning neutron star that's only 12 miles wide. The electric discharge from that little neutron star is responsible for creating this beautiful nebula that glows in X-rays spanning for over 150 light years.
So while most of us use electricity every day without thinking about it, maybe take a moment to look around. The effects of electric discharge are all around us. This simple act of electricity flowing from one point to another is responsible for so many phenomena in our lives here on Earth and beyond that it deserves a little extra attention.