Download What is the relationship between electric force and electric field

Student Responses to Reading Quiz #1, due Friday January 23
Question 1: What is the relationship between electric force and electric field? What are the units
of electric field?
1. the electric force is the "force" that two charges act upon eachother, whereas, the electric field is the
force that a charge acts upon an abitrary point charge per unit charge. Units: N/C (Newtons per Coulomb)
2. F=q*E The units for an electric fields is the Newton Per Coulomb (N/C)
3. The electric field shows the direction of the electric force. The units of electric field is newtons per
coulomb.
4. In order to account for the movement of charges and action at a distance the concept of an electric
field was introduced. The charges produce an electric field, which in turn exerts an electric force on
another charge. An electric field is defined as the force divided by a small test charge. The units of an
electric field are newtons/coulomb (N/C).
5. The electric field of an object is equal to the force at a point divided by the total charge of the object.
The units of an electric field are Newtons per Coulomb.
6. An electric field is what a charge exerts into space, and a field sexerts forces on charges. An electric
force is a force of attraction or repulsion between charges. coluombs
7. Electric force is the force exerted on a point charge q by another charge. An Electric field surrounds a
charge and is what exerts the force on q. Electric fields are in the units N/C (Newtons per Coulumb).
8. Electric field is defined as the electric force on a point charge divided by the point charge itself. It
makes describing the electric force created by a single point in space easier. The units of a field are N/C.
9. F = q E unit of E: N/C
10. Electric force is directly proportional to the electrice field ( Electric field is the electric force divided by
the charge). The units for electric field are newtons per coulomb (N/C).
11. One particle emits an electric field, this field comes in contact with other particles, exerting electric
force. N/C
12. An electric field explains action-at-a-distance. Every charge has an electric field, and this field is the
thing that exerts an electric force on other charges exposed to the field. The charge itself can't exert a
force on another charge when they are separated by some distance, so the electric field the charges put
off create the forces. Electric force is exerted by electric fields.
13. An electric field is produced by one charge everywhere in space and this field exerts the force on the
other charge. Therefore the force is exerted at the position of the second charge. The units of electric field
are the newton per coulomb.
14. An electric point at point p due to a charge at q is the force acting on p divided by the charge of p
(E=F/q) The units of electric field are Newtons per coulomb (N/C)
15. The electric field exerts the electric force. The lectric field has the units Newtons per coulomb.
16. The electric field of a point charge is the electrical force divided by the point charge's charge. The
units of the electric field are N/C.
17. The electric field of a point charge is the electrical force divided by the point charge's charge. The
units of the electric field are N/C.
18. The electric field is the vecter field of forces that would act on charged objects in that area caused by
the electric force, and is measured in newtons per coulombs.
Question 2: What are two differences between a single electric charge (electric monopole) and an
electric dipole?
1. one has one charge, the other has two. Monopoles are insulators, Dipoles are conductors... not sure
2. Dipoles are two equal but opposite charges that are close together. Monopoles have only one charge.
The electric field is proportional to the dipole moment(p=ql) and decreases with the cube of the distance.
The electric field of a monopole decreases with the square of the distance.
3. A single electric charge has either a positive or a negative charge while an electric dipole has two ends
of oppostite charge. An electric dipole can also be neutral overall where a single electric charge will have
some charge.
4. An electric dipole consists of 2 charges equal in magnitude but with opposite sign that are close
together while an electric monopole is simply a point charge. Also in an electric field due to a dipole, the
strength of the field falls off more rapidly with a greater distance. The field falls of proportional to 1/r^2 for
a monopole and 1/r^3 for a dipole.
5. One difference is that the electric field of a dipole decreases by one over the radius cubed, where as a
monopole only decreases at one over R squared. A dipole has two equal charges, where as a monopole
will only have a positive or negative charge.
6. a dipole is when you have two charges and they are oppisite charges
7. An electric charge can be treated as a point charge from anywhere outside of the charge itself while
dipoles can only be treated as a point charge from far away. An electric charge is either positive or
negative while a dipole (treating it as a point charge from far away) is positive on one side and negative
on the other.
8. One: the change in electric field strength decreases more rapidly with distance in a dipole. Two: well,
the dipole has two charges that are equal and opposite seperated by a distance, an electric monopole
has a single charge.
9. - The electric field near the monopole and the dipole (of the same charge) are different - There exists
torques on electric dipoles in non(linearly)uniform electric fields.
10. An electric dipole is a system of two equal, opposite charges separated by a small distance, wheras
an electric monopole is just a single charge.
11. Dipoles contain both + and - charge A dipoles electric field decreases quicker as the distance
increases
12. Their behavior in electric fields are different--a uniform electric field exerts torque on a dipole (not
force), and force on a single electric charge (and therefore acceleration occurs). Also, the magnitude of
the electric field created by a dipole at a great distance is different than that of a single electric charge.
The magnitude of the field created by a dipole at a distance is proportional to the inverse of the distance
cubed, while the magnitude created by a single electric charge is proportional to the inverse of the
distance squared. (1/r^3 versus 1/r^2)
13. A single electric charge causes the electric field to decrease with the square of the distance, while an
electric dipole causes it to decrease with the cube of the distance. Also, within an electric field, the field
will cause torque on the dipole and a force on the single electric charge.
14. if a system has a net charge, electric monopoles exist. if a system has no net charge, only dipoles
exist. The electric field for a dipole decreases more quickly as the distance increases than that of a
monopole.
15. The electric field for a single electric charge is defined as E=kq/r^2 while it is proportional to the dipole
moment and decreases with the cube of the distance in the case of a dipole. The net force on a dipole in
a uniform electric field is 0, however there is a torque applied, this is not the case with a single electric
charge.
16. An electric dipole has an electric dipole moment, and an electric dipole can experience a torque in a
uniform electric field that causes its dipole moment to align with the direction of the field. An electric
monopole cannot experience such a torque.
17. An electric dipole has an electric dipole moment, and an electric dipole can experience a torque in a
uniform electric field that causes its dipole moment to align with the direction of the field. An electric
monopole cannot experience such a torque.
18. An electric monopole consists of a single charged particle, while an electric dipole consists of two
equal and opposite charged particles. Furthermore, the field caused by a monopole falls off proportional
to the distance squared, while the field caused by a dipole drops off proportional to the distance cubed.
Question 3: Describe two pieces of information that you can extract from a picture of electric field
lines.
1. The nature of the source charge (lines pointing in or out) and the magnitude of the source charge
2. Electric field lines leave positive charges and end on negative charges. So, you can determine if a
particle is positive or negative based on the direction of the field lines. From the number of field lines you
can determine the magnitude of the charge
3. The strength of the electric field and the direction of the force exerted on a positive test charge.
4. Depending on the spacing of the lines, one can extract how strong the field is. If closer the lines are
spaced, the stronger the field is. Also the net number of lines either entering of leaving charge can tell you
about the relative sign of the charge. If more lines enter than leave the charge, the charge is said to be
negative. If more lines leave than enter the charge, the charge is said to be positive.
5. You can figure out if the charge is positive or negative, and you can figure out the magnitude of the
charge relative to another charge.
6. Depending on the arrows you can tell which charge it is, and depending on the density you can tell the
field strengh.
7. When there is more then one charge you can tell whether the charges are the same sign, not whether
they are positive or negative but that they are the same or different. If there are two you can tell which
one is stronger or if they are the same by counting the lines leaving and/or going into them.
8. There is a lot of information you can get. You can get an idea of the strength of the field from the
spacing of the lines of force. You can also determine the charge of the particle. Field lines leave postively
charged particles and enter negatively charged ones.
9. - Signs of charges - Intensity of the field
10. The relative strength of the field in different areas according to the line density. Also, the force on a
positive charge will act tangent to the direction of the arrows.
11. 1. Whether particles have similar or different charges 2. The relative strength of the charges (absolute
value)
12. By the direction of the field lines you can tell the charge (positive- radially away; negative- radially in).
You also can determine field strength from the density of the charge lines. The more lines per unit area,
the stronger the field.
13. From a picture of electric field lines, you are able to deduct what the sign of the charge is, for the
arrows point towards a negative charge and away from a positive charge. You are also able to tell the
strengh of the field by the density of lines in that the farther apart the lines are indicates the weaker the
field is.
14. If the field lines are concentrated in an area, then the force acting on a apoint in that area is stronger.
You can also tell the direction the force will act at a point based on the direction the arrows are pointing.
15. The sign of the charges and their strengths are indicated by the field lines.
16. Positive charges can be identified because more lines will begin on them than end on them, and
negative charges can be identified because more lines will end on them than begin on them. In addition,
the density of the lines in a region is proportional to the magnitude of the field in that region.
17. Positive charges can be identified because more lines will begin on them than end on them, and
negative charges can be identified because more lines will end on them than begin on them. In addition,
the density of the lines in a region is proportional to the magnitude of the field in that region.
18. The direction a test charge would travel at any given point, and the relative magnitudes of force on
different points.
Question 4: What (if any) are the conceptual and mathematical issues you are having difficulty
with from the reading?
1. clarify the monopole vs dipole. I'm set on electric fields
2. I'm having a little trouble with the torque on an electric dipole. Also, why isn't there a force on the dipole
in an electric field. The charges are slightly separated, so shouldn't there be a force?
3.
4. I had a little bit of trouble with electric dipoles and the motion of point charges in fields. In terms of
electric dipoles, I was confused about the meaning of an electric dipole moment. Also, because we were
instructed not to memorize or utilize without justification the specialized motion equations it took me a
while to understand how the book was treating the motion of a point charge in a field.
5.
6. not really, i'm just shaky with dot product
7. electric dipole moment. Is its purpose just to tell us how strong the pull is between the charges?
8. No, not really. It all seems pretty straight forward. The electric dipole is a little weird - probably because
I don't really understand what real-world applications it has. I'm sure it has plently, I've just never seen
them before and the book isn't very descriptive.
9. It would be helpful to go over the dipole stuff in class
10. Nothing really.
11. I am not sure if I completely understand 22-6 and 22-7, so a couple of minutes discussing those
sections would be appreciated.
12. Going over the whole electric dipoles in electric fields thing couldn't hurt, but nothing specific really
jumps out at the moment.
13. I was lost on the last section about the torque on a dipole moment. I'm also a little confused on the
whole concept of a dipole, i understand what it is, i think, but i guess i'm just confused about its
application or the importance of it.
14. p. 676 + p. 677 (dipole moments?)
15. none
16. Gravity fields can be thought of as curvatures of space-time; can electrical fields be conceptualized in
a similar, more fundamental way? In a hydrogen atom with one electron and one proton, what is
maintaining the separation distance that exists between the two oppositely charged particles? On p. 662,
Tipler describes that lightning rods work by conducting electrons from the earth to the positively-charged
clouds in order to neutralize them. How do the clouds acquire their positive charges?
17. Gravity fields can be thought of as curvatures of space-time; can electrical fields be conceptualized in
a similar, more fundamental way? In a hydrogen atom with one electron and one proton, what is
maintaining the separation distance that exists between the two oppositely charged particles? On p. 662,
Tipler describes that lightning rods work by conducting electrons from the earth to the positively-charged
clouds in order to neutralize them. How do the clouds acquire their positive charges?
18. None
Question 5: What concerns or issues do you still have with material from previous classes?
1. I feel extremely confident with the material thus far
2. none
3.
4. No concerns or issues. The good amount of assigned problems on caclulating electric forces due to a
system of point charges were very helpful to practice with.
5.
6. none i can think of
7. none
8. None at all that I can think of.
9. none
10. I conceptually understand induction and conduction, but am confused as to when it is termed what.
11. None as of now.
12. I don't think I have any.
13. No concerns or issues that i can think of
14.
15. none
16. None at this time
17. None at this time
18. None
.