MST – ST 589D Electricity
Cynthia Dumayas
Sonnenfeld
MST Student# 900312033
Prof. Richard
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Homework #03 – Applying Coulombs Law and Vectors
Review Questions 10.1-10.10 in Hewitt
1. Which part of an atom is positively charged, and which part is
negatively charged?
Electrons are negatively charged particles found in electron clouds outside the
nucleus. The nucleus is the small, dense positively charged center of the atom. It
contains most of the atom’s mass.
2. How does the charge of one electron compare with that of another
electron?
We can compare the charge of one electron with that of charge of another electron with the
help of coulomb force exert on charge of one electron due to the charge of another electron
and electrons has the same quantity of charge and mass.
3. How do the masses of electrons compare with the masses of
protons?
The proton is much more massive than an electron. It requires more than 1800 electrons to
equal the mass of just one proton. The proton has the positively type of charge and the
electron has the negatively type. Although their charges are exactly the same.
4. How does the number of protons in the atomic nucleus normally compare
with the number of electrons that orbit the nucleus?
Atoms normally have as many electrons as protons, therefore, the atom has zero net
charge.
5. What kind of charge does an object acquire when electrons are stripped
from it?
The object will gain a positively charged.
6. What is meant by saying that charge is conserved?
It means that when something is charged, no electrons are created or destroyed, but are
only transferred from one material to another.
7. How is Coulumb’s law similar to Newton’s law of gravitation? How is it
different?
Both are inverse-square laws; one depends on mass and one depends on charge and
Coulomb’s law works for attraction and repulsion.
8. How does a coulomb of charge compare with the charge of a single
electron?
1 C is the charge associated with 6.25 billion billion electrons that only represents the
amount of charge that flows through a common 100W lightbulb in a little more than a
second.
9. How does the magnitude of electrical force between a pair of charged
particles change when the particles are moved twice as far apart? Three
times as far apart?
It becomes less charge (force decreases). The force varied according to the square of the
distance apart. If you move the particles twice as far apart, the force between them
decreases by a factor of
1
(2)
2
=
1
4
, that is to say, it decreases by a factor of four. If
you move them 3 times as far apart, the force decreases by
1
(3 )
2
=
1
9
10. How does an electrically polarized object differ from an electrically changed
object?
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Electrically polarized objects have had their charges split up, so one side will be positive,
and the other side will be negative. This generally happens when an insulated object is
brought close to (but doesn't touch) a charged object. Electrically charged objects will have
lost or gained charge, so the whole thing will either be positive or negative. If you run a
comb through dry hair a few times, it will become electrically charged. You can then use the
comb to pick up some tiny pieces of paper, because the bits of paper become electrically
polarized.
Exercises 10.1 – 10.7 (Hewitt) Answers:
1. We don’t usually feel electrical forces because the opposite charges which are
positive and negative normally balances out.
2. Electric charge and mass result in an attractive force. Although, charges only result
in an attractive force if the two signs are different. Otherwise, for like charges, a
repulsive force is produced.
3. My hair will then be loses of (negatively charged) electron and the comb gains them.
So, my hair becomes positively charged and the comb becomes negatively charged.
4. Let say that the object touching the ball or to the tip of an electroscope is negatively
charged. The negative charge forces all of the electrons in the ball to move down
towards the leaf, giving them a negative charge. The two leafs, which now have a
negative charge, repel each other.
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neutral. If it were positively charged, it would be slightly because of missing electrons.
7. Because electrons are located on the outside of the nucleus of atoms in electron
shells/orbitals, while
protons located in the nucleus, closely bound together by a strong nuclear force.