My son in the 9th grade asked a question I can't seem to answer. He was
taught that current is a measure of charge in motion-so far so good, but
if you take a piece of glass and build up a charge by rubbing it and then
throw it are you not getting charge and motion ? I am in the electronics field
and told him no, but the more I think about the more I am not sure.

 

My son in the 9th grade asked a question I can't seem to answer. He was
taught that current is a measure of charge in motion-so far so good, but
if you take a piece of glass and build up a charge by rubbing it and then
throw it are you not getting charge and motion ? I am in the electronics field
and told him no, but the more I think about the more I am not sure.

Technically, that is a form of current. You could also say that if you walk past a stationary charged piece of glass, there is current relative to the reference frame that moves with you.

 

The answer is "yes". It's analogous to the current in, say, an ion or electron beam. But, in this case, there just happens to be an inert uncharged chunk of matter moving along with the beam.

You can define current as the movement of charge through a cross sectional area (whether it takes place in a chunk of matter like a conductor or not). This is analogous to the definition of flow of a fluid.

Your son probably owes you a wedgie.

 

The answer is "yes". It's analogous to the current in, say, an ion or electron beam.

But, in this case, there just happens to be an inert uncharged chunk of matter moving along with the beam.

Sir,
What do you mean by "inert uncharged chunk of matter"?

 

Not only is it a current but it is also generating an electromagnetic wave.

Danger Will Robinson! Radiation!