Re: Electrons Going in and out of Filament?

Excellent point!

In this case, you're both right.  The same number of electrons as go into 
a light bulb filament go out, so your science teacher is right here.  
Where *you're* right is in the conservation of energy:  the energy 
carried by the photons is exactly equal to the energy carried by the 
input electrons.  What is happening here is that the input electrons go 
into the filament at a *high* energy, and leave at a *low* energy.  In 
traversing the light filament, the electrons give up some of their energy 
to the filament lattice, causing it to heat up.  The energy is then 
released in the form of photons, causing the filament to glow.  The total 
amount of energy is thus conserved.

Hope that this settles the argument!