Mastering Physics - Electricity Lab
Mastering Physics - Electricity Lab
Mastering Physics - Electricity Lab
Lab 15 (Electricity)
PHY110ASPRING2013
Lab 15 (Electricity)
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Lab 15 (Electricity)
Due: 11:59pm on Friday, May 3, 2013
Note: To understand how points are awarded, read your instructor's Grading Policy.
Electrostatics Tutorial
Work through the tutorial by clicking the image or link below, then answer the questions below.
Electrostatics
Part A
What causes an atom to become positively charged?
Hint 1. Electrons
Electrons are negatively charged.
ANSWER:
Protons were added.
Electrons were removed.
Either protons were added, or electrons were removed.
Electrons were added.
Correct
Removing an electron causes the atom to have more protons, which have a positive charge, than electrons, which have a negative charge.
Part B
If the atoms of one object (initially neutral) have electrons rubbed off through friction with a second object, the first object becomes ________.
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Correct
Since electrons are negatively charged, removing electrons from at atom causes the atom to become positively charged.
Part C
The basic reason why things become electrically charged is that the atoms (or molecules) of some materials hold on to their _______ better than
those of other materials.
Correct
The outer electrons of atoms of certain materials are very weakly bonded, so they can easily be ripped off and transferred to other materials.
Part D
If the distance between two charged objects is doubled, the resulting electric force on each object __________.
Correct
Just like gravity, the electric force is inversely proportional to the square of the distance between the particles.
Part E
In what direction is the electric field at the location depicted by the red cross in the figure?
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Correct
The horizontal components of the electric fields due to each of the two charges exactly cancel out (since the cross is directly above the
midpoint), so only the vertical components add up.
Part F
Object A is attracted to object B and repelled by object C. All three objects are charged. What would happen if object B and object C were brought
together?
Correct
Since one object is attracted to object A and one object is repelled by object A, either object B is positively charged and object C is negatively
charged, or visa versa.
Part G
Object A and object B are both hanging by a string, as shown in the figure. Which statement must be true?
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Correct
Like charges are repelled by each other; it is impossible to determine whether both objects are negatively charged or positively charged based
on the information given.
Part H
What is the main difference between a conductor, such as copper, and an insulator, such as plastic?
Correct
A small electric field within the conductor causes the electrons to drift through the material, conducting electricity.
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Part A
What would happen to the two balls if one of them were kept positively charged and the charge on the other ball were slowly increased, making it
more and more positive?
Correct
Part B
What would happen to the two balls if one of them were kept positively charged and the charge on the other ball were slowly made increasingly
negative?
Correct
Part C
What would happen to the two balls if both of them had a non-neutral charge and you slowly increased the mass of the balls?
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ANSWER:
The angle of the balls with respect to the vertical would decrease.
The angle of the balls with respect to the vertical would not change.
The angle of the balls with respect to the vertical would increase.
Correct
due to
, and
and
and
and
Part A
Rank the six combinations of electric charges on the basis of the electric force acting on
forces pointing to the left as negative. Rank positive forces as larger than negative forces.
Rank from largest to smallest, placing the largest on the left and the smallest on the right. To rank items as equivalent, overlap them.
and
the square of the distance ( ) between them. This result is summarized mathematically by Coulombs law:
.
The direction of the force is such that opposite charges attract and like charges repel each other.
charges?
due to
,
due to
Remember that like charges repel each other and opposite charges attract each other.
ANSWER:
to the right
to the left
There is no force in any direction.
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due to
due to
ANSWER:
to the right.
to the left
There is no force.
, that from
or that from
, is larger
in magnitude?
ANSWER:
the force from
the force from
Neither; they are equal in magnitude.
ANSWER:
to the right
to the left
There is no net force.
Correct
ANSWER:
Correct
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Part A
What is the flow of current proportional to?
Correct
Part B
A pipe is filled with water, and there is a piston at each end. If you apply unequal pressures at the two pistons, which way will the water flow in the
pipe?
Correct
Part C
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What happens to a lamp when you take both ends of the wire connected to it and hold them to the same side of the 12-volt terminal of battery, and
why?
Correct
Part D
What happens when you have a voltage difference between the two ends of the lamp, and why?
Correct
Score Summary:
Your score on this assignment is 93.0%.
You received 3.72 out of a possible total of 4 points.
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