Electric Force and Field Interactive Lab
Proceed in the following order:
Go to this website and observe the various interactions.
Charge transfer with rubbing balloon and resulting forces on balloon or wall
https://phet.colorado.edu/sims/html/balloons-and-static-electricity/latest/balloons-and-staticelectricity_en.html
Answer the questions related to this website on the attached handout.
Conductor vs insulator
http://www.physicsclassroom.com/Class/estatics/u8l1d.cfm
Read this and answer the questions at the bottom on your Handout labeled A
Go to the link to the aluminum can polarization activity and answer the questions on the handout page
page.
Then, at the bottom of the conductor vs insulator portion of the web site click the polarization link and
read about polarization, answering the questions at the bottom of the link in the section labeled B
below
Go visit the Coulombs law interactive applet with questions (works 11-15-15)
Lets you add charges from -5C to 5C and move them and see forces generated
http://webphysics.davidson.edu/physlet_resources/assessment/coulombs_law/part1a.html
Follow the directions (steps 1-11) and sketch out or answer all the questions listed on the
handout labeled C
Go to these web sites and read about the Torsion balance used to measure force between charges
(works 11-15-15)
https://nationalmaglab.org/education/magnet-academy/history-of-electricitymagnetism/museum/torsion-balance-1785
Click on the museum torsion balance link below to see where the torsion balance fits in on a time
line. These topics are all expandable.(works 11-15-15)
https://nationalmaglab.org/education/magnet-academy/history-of-electricitymagnetism/timeline/1775-1799
Now, go to this well done interactive web site about the electric field.
Take your time this is new. The electric field exists in the space around any charged matter.
https://phet.colorado.edu/sims/charges-and-fields/charges-and-fields_en.html
Shows field lines, voltages, lets you add + and minus charges, And move a field detector
Complete the Efield handout.
A.
Conductor Vs Insulator questions
Check Your Understanding
Use your understanding of charge to answer the following questions. When finished, click the button to
view the answers On the web site
1. One of these isolated charged spheres is copper and the other is rubber. The diagram depicts the
distribution of excess negative charge over the surface of two spheres. Describe which is which and
support your answer with an explanation.
See Answer
2. Which of the following materials are likely to exhibit more conductive properties than insulating
properties? Explain your answers.
a. rubber
b. aluminum
c. silver
d. plastic
e. wet skin
See Answer
3. A conductor differs from an insulator in that a conductor ________.
a. has an excess of protons
b. has an excess of electrons
c. can become charged and an insulator cannot
d. has faster moving molecules
e. does not have any neutrons to get in the way of electron flow
f. none of these
4. Suppose that a conducting sphere is charged positively by some method. The charge is initially
deposited on the left side of the sphere. Yet because the object is conductive, the charge spreads
uniformly throughout the surface of the sphere. The uniform distribution of charge is explained by the
fact that ____.
a. the charged atoms at the location of charge move throughout the surface of the sphere
b. the excess protons move from the location of charge to the rest of the sphere
c. excess electrons from the rest of the sphere are attracted towards the excess protons
See An
5. When an oil tanker car has arrived at its destination, it prepares to empty its fuel into a reservoir or
tank. Part of the preparation involves connecting the body of the tanker car with a metal wire to the
ground. Suggest a reason for why is this done.
B
Polarization Link Questions
See Answer
Use your understanding of charge to answer the following questions. When finished, click the button to
view the answers.
1. A rubber balloon possesses a positive charge. If brought near and touched to the door of a wooden
cabinet, it sticks to the door. This does not occur with an uncharged balloon. These two observations can
lead one to conclude that the wall is _____.
a. electrically neutral
b. negatively charged
c. a conductor
d. lacking electrons
See Answer
2. Which of the diagrams best represents the charge distribution on a metal sphere when a positively
charged plastic tube is placed nearby?
3. The distribution of electric charge in a H2O molecule is nonuniform. The more electronegative oxygen
atom attracts electrons from the hydrogen atom. Thus, the oxygen atoms acquire a partial negative charge
and the hydrogen atoms acquire a partial positive charge. The water molecule is "polarized." Which
diagram(s) below correctly portray(s) a pair of H2O molecules? Explain.
See
4. True or False:
When an object becomes polarized, it acquires a charge and becomes a charged object. Why?
See Answer
5. Charged rubber rods are placed near a neutral conducting sphere, causing a redistribution of charge on
the spheres. Which of the diagrams below depict the proper distribution of charge on the spheres? List all
that apply.
See Answer
6. In the above situation, the conducting sphere is ____. List all that apply.
a. charged
C
b. uncharged (neutral)
Coulomb’s Law interactive
c. polarized
See Answer
1. Use the animation to create three like charges at x = -1 m, x = 0 m, and x = 1 m. You can
do this by entering the position in the text box and clicking the add button (position is
given in meters). Sketch a diagram.
2. What is the net force on the middle charge?
3. Now move one of the outer charges around. Sketch your diagram.
4. Is the force on the middle charge still zero? Explain.
5. Push "reset" to clear the charges and set up two identical positive charges 1-m apart.
Sketch your picture.
6. Move one charge toward the other and away from the other. What happens to the force
between the two charges as you change the distance between the charges?
The force between two particles always lies on the line between the two particles, is attractive
or repulsive depending on the signs of the charges, and varies as 1 over the square of the
separation distance (1/r2) (from Coulomb's Law).
7. Add a few charged particles with the same magnitude of charge (and with both positive and
negative sign), and move them around by click-dragging them. Sketch a diagram of
one of your configurations (with the force vectors).
8. Now reset the animation and create two charges with different amounts of charge but of the
same polarity (same sign: either both positive or both negative). Sketch a diagram
and include the force vectors.
9. Describe the similarities and differences in the force vectors on each particle.
10.
11.
Reset the animation and create two charges of different magnitude and opposite
polarity. Sketch a diagram including the force vectors.
Describe the similarities and differences in the force vectors on each particle.