Post on 24-Mar-2018
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Fundamental Particles
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T
True or False:An object that is positively charged contains all protons and no electrons.
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True or False:An object that is negatively charged could contain only electrons with no accompanying protons.
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Identify the following particles as being charged or uncharged. If charged, indicate whether they are charged positively or negatively. (n = neutron, p = proton, e = electron)
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Consider the graphic below of a neutral oxygen atom.
a. Explain what must happen in order for the oxygen atom to become negatively charged.
b. Explain what must happen in order for the oxygen atom to become positively charged.
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Demonstration #1
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Charging an object
Induc2on: To charge by induc0on, you need a Charged Object
Only Conductors can be charged by induc0on.
The process relies on the fact that a charged object can force or induce the movement of electrons about the material being charged.
The object being charged ends up with a charge which is the opposite of the object being used to charge it.
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Electrical forces ____.
a. can cause objects to only attract each other
b. can cause objects to only repel each other
c. can cause objects to attract or repel each other
d. have no affect on objects
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Sample Problem:
A point charge of posi0ve 12.0 μC experiences an aFrac0ve force of 51 mN when it is placed 15 cm from another point charge. What is the other charge?
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a. mass of a charged objectb. # of excess electrons on the object
c. the current of a charged objectd. the distance between charged objects
e. charge of a charged object
a. mass of a charged objectb. # of excess electrons on the object
c. the current of a charged objectd. the distance between charged objects
e. charge of a charged object
The q in Coulomb's Law stands for:
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Two charged objects have a repulsive force of 0.080 N. If the charge of one of the objects is doubled, and the distance separating the objects is doubled, then what is the new force?
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Two charged objects have a repulsive force of 0.080 N. If the charge of both of the objects is doubled and the distance separating the objects is doubled, then what is the new force?
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Two charged objects have an attractive force of 0.080 N. If the charge of one of the objects is tripled and the distance separating the objects is tripled, then what is the new force?
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How is this related to g?
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Field vectors from field lines:
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Consider the electric field lines drawn at the right for a configuration of two charges. Several locations are labeled on the diagram. Rank these locations in order of the electric field strength - from smallest to largest.
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Electrical Potential and Potential Energy
V: Think of it as the gh for an object
U = q V = W = F*d = U = potential energyq = charge
V= potential
All charges want to go to lower potential (b/c U is lower)
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Electric Potential and Potential Energy
We also call this V "voltage"
A battery has "potential" to produce energy
This "potential" is there, even when charges aren't moving.
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U=q V =Fd= q
V=qEd V = Ed
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Let's relate this all to gravity
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Let's relate this all to gravityForce Field
Potential Energy Potential
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Conservation of Energy Review* Conservative forces means energy is conserved
*Electric force is a conservative force
* Energy becomes potential or kinetic depending on position of charge
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The quantity electric potential is defined as the amount of _____.
a. electric potential energy
b. force acting upon a charge
c. potential energy per charge
d. force per charge
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Complete the following statement:
When work is done on a positive test charge by an external force to move it from one location to another, potential energy _________ (increases, decreases) and electric potential _________ (increases, decreases).
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