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64 Cards in this Set
- Front
- Back
The charge of an electron is |
negative |
|
Atomic nuclei of almost all elements consist of |
protons and neutrons |
|
Two like charges |
repel each other |
|
Protons and electrons |
attract each other |
|
The fundamental force underlying all chemical reactions is |
electrical |
|
Electrical forces between charges are strongest when the charges are |
close together |
|
Coulomb's law says that the force between any two charges depends |
• directly on the size of the charges • inversely on the square of the distance between the charges (A and B) |
|
Two charges are separated by a certain distance. If the magnitude of each charge is doubled, the force on each charge is |
quadrupled |
|
When the distance between two charges is halved, the electrical force between the charges |
quadruples |
|
The net charge of a nonionized atom |
is zero |
|
A positive ion has |
more protons than electrons |
|
Conservation of charge means that |
• the total amount of charge in the universe is constant • no experimentalist has even seen a single charge destroyed by itself • electrons by themselves can be neither created nor destroyed • charge can be neither created nor destroyed (all of the above) |
|
If you comb your hair and the comb becomes positively charged, your hair becomes |
negatively charged |
|
To say that electrical charge is conserved means that no case has ever been found where |
net charge has been created or destroyed |
|
A difference between electrical forces and gravitational forces is that electrical forces include |
repulsive interactions |
|
The common hydrogen atom consists of |
one proton and one electron |
|
In a good insulator, electrons are usually |
tightly bound in place |
|
Objects can be charged by |
• induction • friction • touching (all of the above) |
|
Charge carriers in a metal are electrons rather than protons, because electrons are |
• relatively far from a nucleus • loosely bound • lighter (all of the above) |
|
To be safe in the unlikely case of a lightning strike, it is best to be inside a building frame with |
steel |
|
A conductor differs from an insulator in that a conductor has |
• NOT more protons than electrons • NOT faster-moving molecules • NOT more electrons than protons • NOT more electrons than an insulator (NONE of the above) |
|
Much electronic equipment contains transistors and diodes that are made from semiconductors. Semiconductors |
• can be very good insulators • can conduct electricity • contain helpful impurities (all of the above) |
|
A negatively charged rod is brought near a metal can that rests on a wood table. You touch the opposite side of the can momentarily with your finger. The can is then |
positively charged |
|
An electroscope is charged positively, as shown by foil leaves that stand apart. As a negatively charged rod is brought close to the electroscope, the leaves |
move closer together |
|
Lighting bolts occur between |
clouds and the ground clouds (both A & B) |
|
To charge an object by induction, the process of grounding |
may or may not occur |
|
When a charged cloud passes overhead, the ground below is charged by |
induction |
|
Bring a charged object near a conductor and then momentarily touch the conductor. This demonstrates charge by |
induction |
|
A rubbed balloon will stick to a wooden wall, which demonstrates charge |
polarization |
|
Electrical polarization occurs when |
charge distribution in a neutral molecule separates |
|
The reason a charged balloon will stick to a wall is that |
induced opposite charges in the wall are closer than other wall charges |
|
The charge distribution in some molecules is permanently separated into positive and negative regions. Such molecules are called |
electric dipoles |
|
Two charged particles held close to each other are released. As they move, the force on each particle increases. Therefore, the particles have |
opposite signs |
|
Two charged particles held close to each other are released. As the particles move, the velocity of each increases. Therefore, the particles have |
charges that cannot be determined |
|
A positive charge and a negative charge held near each other are released. As they move, the force on each particle |
increases |
|
Two charged particles held near each other are released. As they move, the acceleration of each decreases. Therefore, the particles have |
the same sign |
|
How many different kinds of force would act on a proton placed in both an electric field and a gravitational field |
two |
|
The SI unit of charge is the |
coulomb |
|
Particle A has twice as much charge as particle B. Compared to the force on particle A, the force on particle B is |
the same |
|
The electrostatic force between two charges located 8 meters apart is 0.10 N. What will the force be between these charges when they are located 2 meters apart |
1.6 N |
|
A 2-C charge and a 4-C charge attract each other with 10 N of force. How much will a 2-C charge and a 12-C charge attract each other when placed the same distance apart |
30 N |
|
Two charges separated a distance of 1.0 meter exert a 2.0-N force on each other. If the charges are pushed to a separation of 1/3 meter, the force on each charge will be |
18.0 N |
|
Two charges separated by a distance of 1 meter exert a 20-N force on each other. If the charges are pulled to a 2 meter separation distance, the force on each charge will be |
5.0 N |
|
Two charges separated by a distance of 1 meter exert a 2-N force on each other. If the magnitude of each charge is doubled, the force on each charge will be |
8.0 N |
|
The study of electricity at rest is electrostatics |
true |
|
Electrical forces are strong, but in comparison, gravitational forces are stronger |
false |
|
The reason electrons are attracted to protons is that electrons and protons have the same amount of charge |
false |
|
All electrons are identical; all have exactly the same mass and charge |
true |
|
The total amount of charge in the universe is constant. We have never observed a case of net creation or destruction of charge. |
true |
|
Coulomb's law says that the are two kinds of charges, positive and negative |
false |
|
Coulomb's law for electrical charges has the same mathematical form as Newton's law of gravitation |
true |
|
A material is a good insulator if outer electrons of atoms in the material are free to roam around |
false |
|
A material that is a good insulator of electricity is normally a poor conductor of electricity |
true |
|
Semiconductors can be made to conduct electricity and they can also be made to act like good insulators |
true |
|
When an object is charged by contact, electrons flow from the ground onto the object, or from the object onto the ground |
false |
|
When we allow charges to move onto or off a conductor by touching it with something connected to Earth, it is common to say that we are grounding it |
true |
|
A bolt of lightning is a result of charging by induction |
true |
|
An atom that is electrically polarized vibrates in only one direction |
false |
|
State Coulomb's law. Explain what each symbol in it stands for, and use it to find the force bewteen a 0.002-C charge and a 0.006-C charge that are 10 meters apart |
The force between two charges depends directly on the magnitude of each charge and inversely on the square of the distance between the charges. [eq1] k is the proportionality constant, q₁ and q₂ are the magnitudes of the charges, d is the distance between the charges, and F is the force between the charges. [eq2] |
|
List the similarities and differences between Coulomb's law and Newton's law of gravitation |
Both laws are inverse-square laws and both are directly dependent on the quantities involved; electric charge for electrical force and mass for gravitational force. The Coulomb force is about 1039 times stronger than the gravitational force. Also, the electrical force may be either attractive or repulsive. |
|
Calculate the electrical force between two electrons that are located on opposite sides of an ionized hydrogen atom. Use the following values for the distance and charge size. distance = 5.3 x 10⁻¹¹ m electron charge = -1.6 x 10⁻¹⁹ C |
= 8.2 x 10⁻⁸ N |
|
What is the difference between an insulator and a conductor? which would you guess copper is? Wood? Distilled water? |
A good electrical conductor is any material composed of atoms with "loose" outer electrons that are freeto move about in the material, such as copper. A good electrical insulator is a material composed of atoms that tightly bind electrons. Wood and distilled water are examples of good electrical insulators. |
|
Why should you not stand or sit in water when using electrical appliances? Why is it not a good idea to talk to your friend on the phone while sitting in a bath? |
Ordinary water is a conductor of current. Therefore, when using a plugged-in electrical device, you shouldnot be standing or sitting in water that is connected to Earth. If a short circuit occurs, you may be part ofthe pathway to the ground. For the same reason it is not a good idea to use the phone while taking a bath(although the voltage and current in a phone are relatively low). |
|
What are three ways an object can become charged? How does each work? Give examples |
Objects can become charged by friction, contact or induction.
|