Lecture Text, Electricity
Electricity Lecture
Review main points: This should be a review for those who
have taken High school Physics. For those of you who have not had High
school physics, I recommend you download and study my e-book Force Field
Visualized.
1. Current flows in the direction of E field. That is it
flows from positive to
negative potential.
2. Current normally flows in the direction of arrows on transistors and
diode symbols.
3. Current in wire and resistors is due solely to electron flow.
4. Current in transistor and diodes is due to hole flow.
Holes are positively charged molecules.
5. Positive charged particles flow in the direction of current
and E fields.
6. Negative charged particles flow in opposite direction of
current or E fields.
7. The
electromagnetic force of a battery induces
positive ions to move to the positive plate of a battery.
8.
The electromagnetic force of a battery induces negative ions to move to the negative plate of
a battery.
9. Holes (positively charged molecules) in
silicon crystal lattice carry charge in semiconductors and move in direction of
current. Current is in the direction of E field. Current direction is indicated
by direction of arrow on transistor or diode.
10.About direction of
current.
Case 1: At this very moment a beam of electrons is traveling
from the gun in the back or neck of the CRT directly towards your face (pretend
you are looking at Cathode Ray Tube [CRT] if you have a flat screen
monitor).
Luckily for you the beam strikes the phosphorous coated surface of the CRT
prior to striking you. Now make a fist with your left hand directly
in front of your face. Now point your thump directly in the direction of
your face. Your thump is now pointing in the same direction as the
electron beam. This electron beam produces a magnetic flux that curls
about beam in the direction of the fingers on your left hand. This is a
physical fact of nature not a rule.
Case 2: Next, I want you
to imagine that your CRT was actually an ion propulsion engine and instead of
electrons coming straight at you there were positive ions coming straight at
you. Now make a fist with your right hand directly
in front of your face. Now point your thump directly in the direction of
your face. Your thump is now pointing in the same direction as the
positive ion beam. This ion beam produces a magnetic flux that curls
about the beam in the direction of the fingers on your right hand. This is a
physical fact of nature not a rule.
The Right Hand
Rule states that when you point your thump in the direction of electrostatic
field (E) that is driving the beam, the curl of your fingers indicates the
direction of the Magnetic H field. Note that conventional current also
flows in the direction of electrostatic field. Thus, when you point your
thump in the direction of conventional current, your fingers curl in the
direction of the magnetic field. The right hand rule is the only rule you will need to
remember. What about the case of the electrons hitting the CRT. Just
remember that conventional current is flowing in the opposite direction of the
electrons, then the right hand rule will give you the correct direction of the
curl for the CRT magnetic field. Thus, you only need the Right Hand rule
to determine the direction of the magnetic field curl. This rule could be used by an electronic technician, if he
or she were
trying to wind a coil or was attempting to measure current flow with a
compass. In the real world of technicians, coils and transformers are
labeled, and meters are used to measure current. The remainder of my
lectures will focus on teaching you how to troubleshoot and actually allow you
to self test your ability using my simulations. I also lack the ability to program a Wizard
with artificial intelligence to answer your questions. So, please email me
relevant questions so that I can add a F A Q page to this site.
BilPat4342@AOL.com
