Download Question 1: What is the relationship between electric force and

Student Responses to Reading Quiz #2, due Monday January 26
Question 1: What continuous charge distribution(s) have an electric field that falls off inversely
with distance?
1. lines and disks
2. A finite uniform line charge has an electric field that is inversely related to the distance squared, when
the sample point is far from the charge. If the line charge is infinite, the electric field is inversely related to
the distance
3.
4. The electric Field of a line charge when the line is very long or when we are very near the line charge
drops off inversely with distance.
5. Finite Line Charges
6. The electric field due to an infinite line charge.
7. Infinite Line Charge
8. the electric field produced by an infinite line charge falls off inversely with distance.
9. An infinite plane, a disk, a ring, and lines with continuous charge distributions have an electric field that
falls off inversely with distance.
10. infinite line charges
11. An electric field due to an infinite line charge falls off inversely because its magnitude decreases as
1/y.
12. All but the infinite plane of charge? I'm not sure. At least the infinite line charge does.
13. The continous charge distributions that have electrical fields that fall off inversely are the infinite and
finite lines.
14. A line charge that is either extremely long or viewed from very close.
15. An infinite line charge has an E-field that falls off inversely with distance. (In a proportion of 1 to 1/x)
16. Line, ring, disk, spherical shell, solid sphere.
17. In situations where y << L, the test charge is very close to a line charge or when the line charge is
very long.
18. Those that are sherical or pointlike have ekectric fields that fall off inversely with the distance
19. The electric field due to an infinite line charge has an electric field that falls off inversely with distance.
(The y component of the electric field equals 2k*linear density divided by distance y).
Question 2: How can you obtain a uniform electric field?
1. by placing a point charge inside a spherically symmetric condutor.
2. When the sample point is very far away, the electric field is uniform.
3.
4. A uniform electric field is created when the area of a uniform disk approaches infinity of we get very
close to its surface.
5. Have a constant energy source (not quite sure).
6. If you set up two parallel infinite planes of charge the area confined between the planes will have a
uniform electric field.
7. When sufficiently close to a uniformly charged disk, the disk can be approximated as an infinite plane
of charge, in which case the electric field is uniform.
8. a uniform electric field is achieved when a conductor is in electrostatic equilibrium, which occurs almost
the instant a metal is charged
9. An uniform electric field can be obtained through an infinite plane of charge.
10. infinite plane charges
11. It can be obtained through an infinite plane of charge because in this distribution, the field does not
depend on x.
12. Since an infinite plane of charge puts off a uniform electric field, even when you can't generate an
infinite plane of charge, you can approximate a uniform electric field up close enough to a large enough
disk. If you can come up with some sort of "infinite" plane of charge that'll do it.
13. You can obtain a uniform electric field by have constant energy, which will create a constant force,
which leads to a uniform electric field. (or you have a uniform electric field maker)
14. A uniform electric field is obtained with an infinite plane of charge; that is, a uniformly-charged surface
that is either extremely large or viewed from a very short distance away.
15. Between two oppositely charged plates of equal magnitude, the electric field is uniform.
16. It is formed between two oppositely charged planes that are large compared to the distance between.
17. By putting a charge within or on a spherical conductor.
18. You can obtain a uniform electric field by being a a large distance away from a source charge
19. A uniform electric field can be obtained using a uniform charge distribution. Normally at distances far
away from charge distributions, the electric field will be uniform.
Question 3: Under what (physical) conditions will the electric field inside a conductor be zero?
1. When there is no charge inside the conductor. A hollow copper sphere can be positively or negatively
charged or unetral and as long as there are no charges within the sphere there will be no electric field
inside of it.
2. If the conductor is in electrostatic equilibrium, there is no net field inside the conductor.
3.
4. There will not be an electric field unless there is a source of energy to maintain a current through the
conductor.
5. At electrostatic equilibrium, when there is no energy to maintain a current.
6. In electrostatic equilibrium the electric field inside a conductor must be zero. Since any net charge
resides on the surface, if the conductor is in equilibrium the net flux through the surface must be zero.
Then by Gauss's Law the electric field inside the conductor will be zero.
7. If the conductor has a net charge and there is no source of energy providing constant current, the free
charge will redistribute itself on the surface such that the conductor reaches electrostatic equilibrium. At
this point, the electric field inside the conductor is zero.
8. when a conductor is in electrostatic equilibrium, the electric field inside a conductor must be zero.
9. The electric field inside a conductor will be zero if the condutcor is in electrostatic equilibrium. When
the conductor is in equilibrium, the electric filed will be perpendicular to the surface of the conductor.
10. in equilibrium
11. When there is no source of energy to maintain an electric current and therefore the free charge in the
conductor redistributes itself to create an electre field that cancels the external field within the conductor.
This is known as electrostatic equilibrium
12. When the conductor is in electrostatic equilibrium, the electric field enclosed will be zero. This is when
all of the electric charge, assuming it is free to move and there's no external energy preventing it from
reaching equilibrium, redistributes itself in such a way that a field is created within the conductor that
cancels out all external fields inside the conductor.
13. A electric field inside a conductor will be zero, when the field outside of the conductor is zero.
14. There is no current or source of energy acting on the conductor, and the conductor has reached
equilibrium.
15. If the net charge in a conductor is zero, then the electric field is also zero.
16. In electrostatic equilibrium
17. If there is no net force creating a current inside the conductor the charge will distribute itself so there
is no electric field within the conductor. By using Gauss's Law we can prove that that means the all the
charge will reside on the surface of the conductor.
18. When the conductor encloses a gaussian surface, the net electric field inside is zero (assuming that
there are no charges inside the surface).
19. In electrostatic equilibrium, the electric field inside a conductor is zero. This means there's no source
of energy to maintain a current within the conductor. The free charge will redistribute itsself so that it
cancels out the external electric field within the conductor .
Question 4: What (if any) are the conceptual and mathematical issues you are having difficulty
with from the reading?
1. There are a lot of equations that look kind of confusing now just having read the sections but i see how
they work and will probably be fine with them once we begin to use them.
2. Can we go over the idea about electric field near a uniform plane.
3.
4. I did not understand the explanation in 23-5 on why there is no electric field in a conductor.
5. All of it for the most part. I think that I'll be able to pick it up more after seeing examples and listening in
class than by reading the section.
6. The geometry was a little hard to understand in the pictures when you had to set up an integral in order
to calculate the electric field. I would like to see the steps in class.
7. None
8.
9.
10. none
11. I understand the concepts behind calculating an electric field from Coulomb's Law, I'm just a little
confused on all the math involved.
12. The first question on this quiz. I don't know, I got confused for some reason. I think I'm just being
stupid.
13. 23-5 is a bit confusing
14. None
15. none
16. Charge and field at conductor surfaces About math, I sent you couple of emails.
17. I can't make a lot of sense about why Gaussian surfaces are special - but that will probably make
more sense if we go over any of the chapter in class. Otherwise, my math skills are rusty, but everything
looks familiar so I'm not too worried.
18. No problems yet with the reading
19. In Section 23-5, were we supposed to know that the magnitude of charge from the electric field from
near the point and from the rest of the charge was the surface charge density / 2Eo? The superposition of
these fields makes sense, but I'm uncertain were the values of the fields themselves came from.
Question 5: What concerns or issues do you still have with material from previous classes?
1. none
2.
3.
4. none
5. More work on using the equations with Dipoles see #6
6. No concerns or issues.
7. None
8.
9.
10. none
11. none
12. I'm good, I think.
13.
14. None
15. none
16.
17. none.
18. Concerning dipoles, what exactly is the book referring to as p, the dipole moment
19. None, really.