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22 Cards in this Set
- Front
- Back
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Immediately after a plastic rod is givenn a net negative charge by rubbing it with fur, the fur
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Has an equal positive charge
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metals are the best thermal conductors as well as being the best electrical conductors. Is there any connection between the two?
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Yes, since the free electrons that make a metal a good electrical conductor also make it a good thermal conductor
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a teflon rod was given a net negative charge by rubbing with with fur. The rod was touched to an empty aluminum can and a faint popping sound was hear, indicating what change had transferred to the can. When the rod was held next to the can, the can
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was attracted to the rod
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A teflon rod was given a net negative charge by rubbing it with fur. the rod was held near but not touching the terminal of an electroscope. The electroscope was grounded by touching it. The ground was broken and the rod was removed. The electroscope
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had a positive charge
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differences between Coulomb's law and Newton's law
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- The constant in Coulomb's law is much greater than the constant in Newton's law
- gravity is always attractive; the electrostatic force can be either attractive or repulsive |
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The force between two point charges is 1N. The charges are moved so they are four times as far apart. The force between the charges is now
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1/16 N
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What force(s) hold(s) the hydrogen atom together
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the electromagnetic force
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A -1.0uC point charge is placed at a point where it experiences an electric force of .025N, down. The electrical field at that point is
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25,000 N/C, up
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Why can't electric field lines cross?
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at the point where they cross the field would have two different directions at the same time, which is not possible
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Why is the inside of a car a safe place to be during a thunder and lightening storm?
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the car is metal. The electrostatic field inside a conductor is zero
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According to Gauss's law, why is the electrostatic change on a conductor on its surface
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the electrostatic field inside a conductor is zero
the electric flux through the Gaussian surface is zero there is no change enclosed by the Gaussian surface |
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A charge is initially at rest in an electric field. Which of thefollowing correctly describes how the charge will move?
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A negative charge will move from lower to higher potential; a positive charge will move from higher to lower pitential
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What is the main advantage of using electric potentialinstead of electric potential energy?
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the potential of a point is space is independent of the sign of the charge placed at the point
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What is the direction of the electric field in a parallel platecapacitor?
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From the positive plate to the negative plate
From high potential to low potential |
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A parallel plate capacitor is charged by connecting it to abattery. Which of the following statements is/are correct?
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The plate has a net charge of zero but each plate has the same charge as the side of battery
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A parallel plate capacitor was charged by a battery andthen was disconnected from the battery. What happenedto the voltage across the capacitor when the plates weremoved farther apart?
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the voltage increases
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According to the equation the energy storedby a capacitor is proportional to its capacitance whileaccording to the equation the energy storedby a capacitor is inversely proportional to its capacitance.Is this a contradiction?
PE = .5CV^2 PE = .5Q^2/C |
No, because potential energy can be proportional or inversely proportional to capacitance, but not at the same time
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Which devices had a graph with a straight line
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a resistor, not a light bulb or a diode
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Which of the following does a resistor use up
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electric energy
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The resistivity of copper is less than the resistivity ofaluminum. Can a copper wire and an aluminum wire ofthe same length have the same resistance?
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Yes, if the aluminum wire is thicker
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The temperature coefficient of resistivity of asemiconductor is negative (i.e. the resistance decreaseswith increasing temperature). How could this be explainedby the microscopic model of resistivity?
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The number of charge carriers in a semiconductor increases with increasing temperature
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What is the main differencebetween alternating current(ac) and direct current (dc)?
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charges only move in one direction in dc; their direction of motion changes in ac
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