Charges
When an object gains or loses charge, what particle is being transferred?
An electron
If the distance between two charges is quadrupled (4x), what is the new force?
F/16
Electric field lines start from _________ charges and end on _________ charges.
Electric field lines start from positive charges and end on negative charges.
Electric Potential is _________ per _________.
A volt is a _________ per __________.
Electric Potential is Electric Potential Energy per Unit Charge.
A volt is a Joule per Coulomb.
What are the 4 main processes of charging?
Friction, Induction, Conduction, Polarization
How does an object gain a positive charge?
It gives up some electrons
A +5.0 μC charge and a -6.0 μC charge experience an attractive force of -0.72 N ("-" means attractive).
Determine their separation distance.
0.61m
How are electrons arranged on a conductor and what is the electric field inside the conductor?
The electrons are arranged on the outside of a conductor. Since the fields cancel each other out, the electric field inside the conductor is zero.
Explain why touching an electric fence is far more dangerous than touching a Van Der Graaf generator.
If I rub a balloon through my hair such that it becomes positively charged, why does it stick to the wall?
Polarization, the electrons on the wall realign so that more electrons are on the side of the wall closer to the balloon (Note: The wall is still neutral), and so the positively charged balloon will stick to the negative side of the wall.
Opposite charges _______ and same charges ________.
Opposite charges repel and same charges attract.
A balloon with a charge of 4.0 x 10-5 C is held a distance of 0.10 m from a second balloon having the same charge. Calculate the magnitude of the repulsive force.
1440N
In a diagram with electric fields, where is the electric field the strongest?
Where the lines are closest together
How does the electric potential change as I bring a proton and an electron closer together?
The electric potential decreases. Protons and electrons are attracted to each other. Thus the closer they are to each other, the less work I have to do to get them in that position. Since the amount of potential energy is determined by how much work was done to get them in that position, the closer they are, the less potential energy they have.
What does it mean to "ground" an object?
Grounding an object means connecting a charged object to a "ground" (an object with a large number of electrons) so that electrons can either flow into or leave the charged object to balance out the charge near the connection.
Both spheres have a charge of -2C, because the charges will balance out so that the charges on both spheres are equal.
The force between two charges is -24N. If the distance between the charges is quadrupled, and the charge on BOTH of the charges is doubled, what is the new force between the two charges?
-6N
Draw the electric field lines for a capacitor.
Lines going from the positively charged plate to the negatively charged plate, equally spaced apart.
How does the electric potential of a proton change as I bring it closer to another proton?
Protons repel each other, so in order for me to bring the proton closer to another proton, I have to do work. That work increases the potential energy of a proton.
Explain the process of charging an object frictionally.
When you rub two objects together, electrons will be stripped from the object with a lower electron affinity and given to the object with a higher electron affinity.
6 x 1.6 x 10-19 C = 9.6 x 10-19 C
What is the force of attraction between a 22 gram balloon with a charge of -2.6 μC and a wool sweater with a charge of +3.8μC?
-0.158N
4 protons are placed so that the protons are on a line and evenly spaced apart with a distance of 1.0m between each proton. If I place an electron in the middle of all the protons, what is the net force on the electron?
There is a potential difference of 10V between the positive and negative ends of a battery. How much energy is required to move a charge of 6.0 x 10-6 C from the positive to the negative side?
6 x 10-5 J
An aluminum electrophorus (think of the lab we did) is moved to be right on top of, but not touching, a negatively charged styrofoam plate. Draw the distribution of charges on both the plate and the electrophorus after you ground it, and explain what happens when you touch an LED to the electrophorus.
Styrofoam plate has a bunch of negatives on the top, aluminum electrophorus has a bunch of positives on the bottom.
Electrons move from your hand through the LED to balance out the positively charged aluminum electrophorus.