1. Mar 5, 2007

### pugfug90

I have the multiple choice part of my electrostatics test back and I'll be sure to update the other thread once I get that part up

1.*When electrons are transferred from one object to another, positive and negative charges are _____. "created", "reversed", "separated", "canceled" I put "separated" but his answer is "created".. I thought energy is neither made nor destroyed.. Hmm.. And by electrons transferring from one object to another, don't "neutral" objects have a certain # of electrons and protons.. eventually one object has more electrons, one has more protons if they're transferring.. Or maybe.. A "created" charge doesn't mean new protons/electrons, but that 2 neutral objects have suddenly "earned" a positive or negative charge, therefore, "created"?

2.*What isn't true about a charged object? I'm sure his answer is right, but just to make sure.. If it's not true "that electrons always flow from negative to positive"..
http://www.physics.miami.edu/~zuo/class/fall_05/supplement/Figure21_26.jpg
Basing of that pic, would it be true that "positive goes to negative"? But from the electroscope things we did, I thought protons were too "heavy" and only electrons moved..

3.*When neutral objects are rubbed together, there is a transfer of electrons. The resultant net charges on the two materials are His answer is "unlike and equal". I kind of get it now.. If an object A loses 50 electrons to object B.. Object B becomes -50 ?coulombs? [correct term here?] and object A becomes +50.. So yeah, basically, I'd like to know the correct terminology here.
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^&$*A conductor which is connected to a negatively charged electroscope is touched with a glass rod having a positive charge. Which will occur? We have diagrams for these problems. The correct diagram is a neutral diagram.. *A rubber rod becomes negatively charged when rubbed with fur. After rubbing the rubber rod, the fur is touched to an initially uncharged electroscope.. Which will occur? The answer is a positive electroscope with the leaves separating because of positives.. Umm..? I'm pretty sure that the answer should be a negative electroscope, with separating leaves as a result of the negatives.. *An insulator which is connected to a positively charged electroscope is touched with a negatively charged rod. What will happen?His answer is a positive electroscope with dividing positive leaves.. If ^&$ is neutral.. Isn't this just the exact same thing, kind of?

Thanks
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Yellow parts understood now, still up for reference.

Last edited: Mar 5, 2007
2. Mar 5, 2007

### cristo

Staff Emeritus
Your second part is correct. The question doesn't say that protons and neutrons are created, but that each object receives a net charge (i.e. a charge is "created" since it changes from no net charge to some net charge)

I don't really know what you want me to say here!
If an atom loses an electron it will have a charge of +1, or 1.6x10-19C. The "+1" would have units "e" where e denotes the elementary charge (the charge on a proton)

As for the rest of your questions, I don't really know anything about electroscopes, so can't really help.

Just out of interest, what is the point of this thread? Do you really not trust your teacher to mark your test correctly?

3. Mar 5, 2007

### pugfug90

"Do you really not trust your teacher to mark your test correctly?"
I wouldn't say "not trust".. Just making sure:D One time, I corrected this one answer of his on a quiz..and everyone who got the same answer as me got a +3 or something

"I don't really know what you want me to say here!"
*What isn't true about a charged object?
a)it may attract another charged aobject
b)it may repel another charged objects
c)it always attracts a neutral object
d)electrons always flow from the negative to the positive

The answer he says is "right", as in not true about charged objects is "d )electrons always flow from the negative to the positive"
Then what does this image mean?
http://www.physics.miami.edu/~zuo/class/fall_05/supplement/Figure21_26.jpg
"Positives" are flowing to negatives.. But learning about electroscopes, I thought that proton's mass makes them can't move, and it is the electrons that do all the busy work..

Last edited: Mar 5, 2007
4. Mar 6, 2007

### pugfug90

bump? =+=+=+=+=+=