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Chapter 32: Elelctrostatics
Terms in this set (46)
Which force-gravitational or electrical repels as well as attracts?
Electrical repels and attracts while Gravitational only attracts
Gravitational force depend on the property called Mass. What comparable property underlies electrical force?
How do protons and electrons differ in their electrical charge?
Same magnitude but different charge
Is an electron in a hydrogen atom the same as an electron in an uranium atom?
Yes, all electrons are identical
Which has more mass- a proton or an electron?
Proton- more than 1800 times greater than the electron
In a normal atom, how many electrons are there compared with protons?
Same number, no net charge
How do like charges behave toward each other?
Repel each other
How do unlike charges behave toward each other
Attract each other
How does a negative ion differ from a positive ion?
A negative ion has extra electron(s); a postive ion has lost electron(s)
What does it mean to say that charge is conserved?
It is neither created nor destroyed, only transferred
If electrons are rubbed from cat's fur onto a rubber rod, does the rod become positively or negatively charged?
The rod will have excess electrons so the rod will be negatively charged
If electrons are rubbed from cat's fur onto a rubber rod, does the cats fur become positively or negatively charged?
The cat's fur will have excess protons and be positively charged
How is Couloumb's Law similar to Newton's law of gravitation?
Both are inverse-square laws
How is Couloumb's Law different to Newton's law of gravitation?
One depends on mass, and one depends on charge; Coulumb's law comprises both attractive and repulsive forces
The SI unit of mass is the kilogram. What is the SI unit of charge?
The proportionality constant k in Coulumb's law is huge in ordinary units, whereas the proportionality constant G in Newton's law of gravity is tiny. What does this mean in terms of the relative strengths of these forces?
Electrical force is relatively much greater
Why are metals good conductors?
Metals hvae free electrons; Metal is a good conductor because their electrons can move more freely than those non metals. The structure of a metal's atom electron cloud makes it easy for metals to gain or lose electrons.
Why are materials such as rubber and glass good insulators?
They bound electrons; Rubber and glass are good insulators because their properties will cause electrons to slow down and eventually prevent them from moving at all. Keeping electricity bound within its materials.
What is a semiconductor?
Can behave either an insulator or conductor. It normally acts like an insulator but when energy is applied, becomes a conductor
Which two methods of charging objects involve touching?
Conduction and friction
Which method of charging objects involves no touching?
What is lightning?
Electrical discharge from cloud to cloud or to ground
What is the function of a lightning rod?
To prevent discharge and conduct charge to ground
What does it mean to say an object is electrically polarized?
Negative on one side and positive on the other side
When a charged object ploarizes another, why is there an attraction between the objects?
The oppositely charged side is a little closer
What is an electric dipole?
A molecule in which the distribution of charge is uneven
Electrical forces between charges are enormous relative to gravitational forces. Yet, we normally dont sense electrical forces between us and our environment, while we do sense our gravitational interaction with Earth. Why is this so?
Charges can cancel, while masses cannot; There is no electrical force between us and the earth because neither of us is charged! But we do both have mass, so gravity acts but electricity doesn't
Two equally charged particles exert equal forces on each other. Suppose that the charge on one of the particles is doubled. The charge on the other remains the same. How much stronger is the force between them?
Doubling the charge on one of the particles produces twice the force.
Two equally charged particles exert equal forces on each other. Suppose that the charge on one of the particles is doubled. The charge on the other remains the same. How does the force change if the charges of both particles are doubled?
Doubling the charge on bothe particles produces 4x the force
How will the forces between two charged particles compare whne one particle has ten times as much charge as the other?
The force will be equal in magnitude in accord with the Newton's third law.
If electrons were positive and protons negative, would coulumb's law be written the same or different?
The same, the coulumb's law doesnt distinguish between positive and negative charge; it distinguishes the magnitude of the electrostatic force of attraction.
If you scuff electrons from your hair onto a comb, are positively or negatively charged?
How about the comb?
The comb took electrons from your hair, making the comb negatively charged. Since your hair lost/gave electrons, your hair now has an abundance of protons, making your hair positively charged.
The five thousand billion billion freely moving electrons in a penny repel one another. Why don't they fly out of the penny?
The electrons are attracted to the same number of protons in the Penny; The electrons' negative charges are balanced by the positively charged atomic nuclei in the penny. The attraction between the positive and negative charges keep the electrons in the penny
If a glass rod that is rubbed with a plastic dry cleaner's bag acquired a certain charge, why does the plastic bag have exactly the same amount of opposite charge?
Law of conservation of charge states that charge can't be created or destroyed, so charge is only transferred. Total charge before = total charge after
Why do clothes cling together after tumbling around in the dryer?
An effect from static electricity called static cling. Clothes rub together and against the metal inside the dryer causing electrons to transfer from one item to another by friction. Some clothes come out positively charged and others come out negatively charged.
Why will dust be attracted to a CD wiped with a dry cloth?
During the wiping process, electrons are transferred to the cloth from the CD or to the CD from the cloth. The CD becomes charged, and produced an electric field which polarizes the surrounding dust. The dust is then attracted to the charged CD, building up a static charge.
When one material is rubbed against another, electrons jump readily from one to the other, but protons do not. Why?
Protons are locked ointo the nuclei of atoms but electrons are not
Plastic wrap becomes electrically charged when pulled from its container. Does the charged wrap stick better to glass bowls or metal bowls?
Plastic wraps wtick better to the non-conducting glass. It sticks poorly to conducting metal
Explain how an object that is electrically neutral can be attracted to an object that is charged
The side having the opposite charge is closer to the charged object. The attraction between the opposite charges is greater than the repulsion between the like charges.
When an electroscope is charged, why do the leaves move from a neutral vertical position to springing apart?
When the electroscope is touched, it is charged by conduction, making the leaves of the electroscope also charged. Although, since the leaves have the same charge, they move away from each other because alike charges repel, so the leaves repel.
Does the electroscope need to be touched to have the leaves move?
No, the leaves could repel by being charged by induction too. When the charged object comes close, it polarizes the electroscope making it temporarily charged.
Comb attracting bits of paper with no charge. If the comb were positively chaged, would it attract the same bits of paper?
Yes, either a positive or negative charge will polarize and attract the paper
When the body of the car is given a sudden electric charge and the misr of paint is attracted to it, the car is painted. How?
The paint is polarized and attracted to the conducting surface
Which case would the moving particle have the greater speed when the collision occurs? why?
Electron, the force on both will be the same but the electron will have more acceleration and therefore more speed because of its lesser mass
Jess says the force on the particles decreases with distance, and their speed will be less. Marie says no, the speed of the repelled particles increases as long as they interact with each other. Whom do you agree?
Marie, Acceleration, not speed, decreases with increasing distance
Which has the greater initial acceleration if the intial distance between the particles is the same
It is correct to say equal forces but not equal accelerations. Also, the greater the mass of the protons means less acceleration for the same force.
the evidence considered least appropriate by auditors is best described as
What properties of metals contribute to their tendency to form metallic bonds?
How do igneous rocks change into sedimentary rocks?
The greatest number of relationships between the organisms in an ecosystem is best shown in
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