I would lOVE to do a weekly quiz installment…of basic electrical and electrical training questions…you give the word and I will do a weekly, daily or so on program for it.
You know Joe…those are the 3 that would KILL you in the field…tehehhe…Don’t worry I got the same ones wrong on the Lawyer Bar Exam as well…thehehehe…the exact same numbers…:mrgreen:
Scores
14 of 14 100%
13 of 14 93%
12 of 14 86%
11 of 14 79%
10 of 14 71% If 75% or better was required to pass this or less would be failing. More studying would be in required.
I breezed right through that thing…then I saw the answers!!
Oh, well…
Actually, I only got two wrong–one was #7 and I don’t know why.
I remember in college on the final exam for one course in music I missed one
question–I answered 5/8 time as symetric. Well none of us are perfect.
always read and re-read the question and don’t get in a hurry–the bus will wait for you.
Why not make this a course like the online Roofing Course that we have on our site now and upon completion we can get the hours needed for continuing education. Just a thought.
I don’t think the powers that run this board want me anywhere near helping out in that fashion. I am here to help when needed and I will post quizes and information to help…until they kick me off I guess…lol
Never really thought about it but off the cuff I would say it is the basis for the ‘flow’ of electricity.
Not in the US.
In the US you get 208/120 or 240/120.
Root Mean Square.
The root-mean-square of a variate X, is the square root of the mean squared value of X
In this case it is the square root of the mean squared value of a voltage reading.
That is quite literally the voltage measurement from the ‘top’ to the ‘bottom’ of an AC sine wave.
If you measure a ‘120 volt’ outlet with a 'scope you will see about 180 volts peak to peak.
You stumped me there.
A note on true RMS multimeter’s they are nice to have but not necessary for residential work. True RMS meters are need when the frequency of the voltage is other than 60 cycles, which in industrial work is often the case.
Note that this satisfies Newton’s third law because it implies that exactly the same magnitude of force acts on q2 . Coulomb’s law is a vector equation and includes the fact that the force acts along the line joining the charges. Like charges repel and unlike charges attract. Coulomb’s law describes a force of infinite range which obeys the inverse square law, and is of the same form as the gravity force.
Electric Potential Energy
Just like in the gravitational case, the potential falls proportional to r*-1*. The form of the potential energy U looks the same as the that for the force F except for the power of r.
Again, note that the potential energy is positive when the two charges have the same sign and negative otherwise. Note that the potential energy of a set of charges, qa,qb,…q**zis the sum of the potential energies of the pairs. For instance, if there are 3 charges, qa,qb,qc, the net potential energy is:
Forces between two electrically-charged objects can be extremely large. Most things are electrically neutral; they have equal amounts of positive and negative charge. If this wasn¹t the case, the world we live in would be a much stranger place. We also have a lot of control over how things get charged. This is because we can choose the appropriate material to use in a given situation.
Metals are good conductors of electric charge, while plastics, wood, and rubber are not. They¹re called insulators. Charge does not flow nearly as easily through insulators as it does through conductors, which is why wires you plug into a wall socket are covered with a protective rubber coating. Charge flows along the wire, but not through the coating to you.
Materials are divided into three categories, depending on how easily they will allow charge (i.e., electrons) to flow along them. These are:
conductors - metals, for example
semi-conductors - silicon is a good example
insulators - rubber, wood, plastic for example
Most materials are either conductors or insulators. The difference between them is that in conductors, the outermost electrons in the atoms are so loosely bound to their atoms that they¹re free to travel around. In insulators, on the other hand, the electrons are much more tightly bound to the atoms, and are not free to flow. Semi-conductors are a very useful intermediate class, not as conductive as metals but considerably more conductive than insulators. By adding certain impurities to semi-conductors in the appropriate concentrations the conductivity can be well-controlled.
There are three ways that objects can be given a net charge. These are:
Charging by friction - this is useful for charging insulators. If you rub one material with another (say, a plastic ruler with a piece of paper towel), electrons have a tendency to be transferred from one material to the other. For example, rubbing glass with silk or saran wrap generally leaves the glass with a positive charge; rubbing PVC rod with fur generally gives the rod a negative charge.
Charging by conduction - useful for charging metals and other conductors. If a charged object touches a conductor, some charge will be transferred between the object and the conductor, charging the conductor with the same sign as the charge on the object.
Charging by induction - also useful for charging metals and other conductors. Again, a charged object is used, but this time it is only brought close to the conductor, and does not touch it. If the conductor is connected to ground (ground is basically anything neutral that can give up electrons to, or take electrons from, an object), electrons will either flow on to it or away from it. When the ground connection is removed , the conductor will have a charge opposite in sign to that of the charged object.
An example of induction using a negatively charged object and an initially-uncharged conductor (for example, a metal ball on a plastic handle).
(1) bring the negatively-charged object close to, but not touching, the conductor. Electrons on the conductor will be repelled from the area nearest the charged object.
(2) connect the conductor to ground. The electrons on the conductor want to get as far away from the negatively-charged object as possible, so some of them flow to ground.
(3) remove the ground connection. This leaves the conductor with a deficit of electrons. (4) remove the charged object. The conductor is now positively charged.
P.S…If you really want to learn some NEAT stuff…click on the links in the above posting…That learning site is awesome.
Ok…How does this apply to Home Inspectors…If you do not know the basics of electricity…you simply can’t say you have a background in Electricity when it come to home inspections…these are basic principles plus it is just plain fun…who wants to look at violation picture all the time.
