Physics II Quiz Two

A neutral object contains no charges. True False

False

True or False Rubbing two materials made of the same substance will charge them

False

True or False Two charged insulators can be rubbed together and the charge will be distributed evenly

False

A neutral metal sphere is touched by a positively charge metal rod. During the process, protons are transferred from the _____ to the _____ and the sphere acquires a _____ charge. charged rod, neutral sphere, negative charged rod, neutral sphere, positive neutral sphere, charged rod, negative neutral sphere, charged rod, negative Nonsense! None of these describe what occurs.

Nonsense! None of these describe what occurs.

coulomb

SI unit of charge

A group of students in another class is studying the effects of charged objects. The students suspend three uncharged conducting spheres, A, B, and C, from insulating threads so that they touch each other as shown in the before figure below. One of the students then holds a negatively charged rod near, but not touching sphere A. While the negatively charged rod is still in place, another student moves spheres B and C away from each other as shown in the after figure. How will the spheres be charged, if at all? Sphere A is positive; Sphere B is negative; Sphere C is neutral. Sphere A is negative; Sphere B is negative; Sphere C is positive. Sphere A is neutral; Sphere B is positive; Sphere C is negative. Sphere A is positive; Sphere B is neutral; Sphere C is negative. Sphere A is positive; Sphere B is positive; Sphere C is negative.

Sphere A is positive; Sphere B is neutral; Sphere C is negative.

When an object becomes charged by rubbing, where do the electric charges come from? The electric charge comes from the surrounding air. The electric charge is created by rubbing energy. The process of rubbing leads to a redistribution of charge. The rubbing process has destroyed electrons in the positively charged object.

The process of rubbing leads to a redistribution of charge.

Suppose you wanted to give an initially neutral object a total charge of +12 pico-Coulombs (pC). How many electrons would you need to remove from the object? Answer:

74906367

Select ALL statements below that are TRUE about an initially neutral, insulating object A when a charged object B is brought close to, but does not touch, A: A and B will be attracted regardless of the charge of B. A and B will repel if B has a net positive charge. Because A is neutral, there will be no charge interaction between A and B. In order for A and B to experience an electric interaction, there must be a transfer of charge from B to A. The presence of B will change the distribution of negative charges in A.

A and B will be attracted regardless of the charge of B., The presence of B will change the distribution of negative charges in A.

Suppose you have three conducting spheres, A, B, and C. Sphere A has a net charge of +3 micro-coulombs. Sphere B has a net charge of -3 micro-coulombs. Sphere C is neutral. You first touch sphere A to sphere C and then separate the two. Next you touch Sphere B to sphere C and separate the two. What is the final charge on sphere C? Give your answer in micro-coulombs. Answer:

-0.75

charge or proton/electron

1.602 x 10^-19 C

Which of the following processes are likely to produce electrically charged objects? Walking across a nylon rug. Gasoline flowing through a rubber hose. Water droplets moving through the atmosphere. Petting a cat. All are likely to produce charged objects.

All are likely to produce charged objects.

grounding

Allowing charges to move freely along a connection between a conductor and the ground.

You're investigating the charge of several objects. You observe that Object C attracts Object B, Object D repels object C, Object E attracts D, but repels F, and Object F attracts A. You are told that Object A is negatively charged and Object B is electrically neutral. For each object (C, D, E, and F), select ALL possible charge states consistent with the observations. C could be positively charged C could be negatively charged C could be neutral D could be positively charged D could be negatively charged D could be neutral E could be positively charged E could be negatively charged E could be neutral F could be positively charged F could be negatively charged F could be neutral

C could be negatively charged, D could be negatively charged, E could be positively charged, F could be positively charged

A metal sphere is electrically neutral. It is touched by a positively charged metal rod. As a result, the metal sphere becomes charged positively. Which of the following occur during this process? The metal sphere gains some protons. Electrons are transferred from the sphere to the rod. The metal sphere loses electrons. The overall charge of the system is conserved. Protons are transferred from the rod to the sphere. Positive electrons are moved between the two objects.

Electrons are transferred from the sphere to the rod. The metal sphere loses electrons. The overall charge of the system is conserved.

You can remove electric charge from your clean slacks by rubbing a metal clothes hanger down the inside of the slacks. Which answer below represents the best explanation for why this works? The charge travels from the cloth to the metal to your hand through your body to the ground. The metal hanger absorbs all the charge. The metal causes tiny sparks that send the charges into the air. The metal provides charge to the cloth that neutralizes its charge. None of these answers is responsible.

The charge travels from the cloth to the metal to your hand through your body to the ground.

A positively-charged glass rod is touched to the plate of a neutral electroscope. Upon contact, the electroscope becomes charged and the needle deflects. Which of the following statements are true of the charged electroscope? The electroscope is now charged positively. The electroscope and the glass rod now have the same type of charge. The electroscope lost all of its electrons during the charging process. During the charging process, some electrons left the electroscope and entered the glass rod. The electroscope gained electrons during the charging process. The electroscope needle will deflect even more if the glass rod is brought near it again.

The electroscope is now charged positively. The electroscope and the glass rod now have the same type of charge. During the charging process, some electrons left the electroscope and entered the glass rod. The electroscope needle will deflect even more if the glass rod is brought near it again.

A physics teacher rubs a glass rod with a felt cloth causing the glass rod to become positively charged. Which of the following statements are TRUE? Select all that apply. The glass gained protons during the rubbing process. The felt became charged negatively during this rubbing process. Charge is created during the rubbing process; it is grabbed by the more charge-hungry object. If the glass acquired a charge of +5 units, then the felt acquires a charge of -5 units. This event violates the law of conservation of charge. Electrons are transferred from the glass to the felt; protons are transferred from the felt to the glass. Once charged in this manner, the glass rod and the felt cloth should attract each other. In general, glass materials must be willing to accept electrons while felt must be willing to give up its electrons.

The felt became charged negatively during this rubbing process. If the glass acquired a charge of +5 units, then the felt acquires a charge of -5 units. Once charged in this manner, the glass rod and the felt cloth should attract each other.

True or False A charged insulator maintains the charge on the surface and it does not spread throughout the material

True

True or False Charge is conserved

True

True or False Insulators are used to prevent charge from moving where it is not wanted

True

True or False It is possible to charge a conductor without touching it

True

How many fundamental types of electric charge are there? One Two Three

Two

system

any collection of interacting objects

Match the charge state of the object pairs to the type of electric interaction they would experience. Neutral/Positive Negative/Neutral Positive/Negative Negative/Negative Neutral/Neutral Attraction, Repulsion, No Interaction

attraction, attraction, attraction, repulsion, no interaction

Upon entering the room, you observe two balloons suspended from the ceiling. You notice that instead of hanging straight down vertically, the balloons seems to be repelling each other. You can conclusively say ... the balloons have opposite charges. there is nothing you can say conclusively. both balloons have a positive charge. both balloons have a negative charge. both balloons have the same charge.

both balloons have the same charge.

All materials contain ____________ types of charge, most materials are _____________ meaning they have both positive and negative charges, some materials donate their electrons while others readily ________________ them. Materials that allow movement of negative charges are _______________, materials that do not allow movement of negative charges are ___________________.

both, neutral, accept, conductors, insulators

electrostatic charge interaction

causes a change in the arrangement of charges within one or more objects

Suppose you are doing an experiment in a lab, which requires you to determine whether an object is charged and what the sign of the charge is. You bring the object near a neutral electroscope but not touching it. You observe the leaves of the electroscope move apart. From this one observation, you can tell that the object is positively charged negatively charged neutral charged but we cannot determine the sign of the charge. cannot tell whether the object is charged at all.

charged but we cannot determine the sign of the charge.

An electric charge interaction occurs between two nearby _______________ objects. Two like-charged objects will ____________, whereas two charged objects will ________________

charged, repel, attract

turboelectric effect

charging two different materials by rubbing them together

charged insulator and neutral conductor TOUCH

conductor become charged the same as the insulator

An uncharged ______________can become charged by touching it with a negatively charged object. Some of the excess electrons can be transferred to the ___________________ where they spread out evenly over the surface of the conductor. When two charged conductors touch, the net charge is distributed _______________.

conductor, conductor, evenly

All electroscopes operate in the same way and each part is a _____________ allowing electrons to move throughout. Objects are held nearby the plate thus inducing the _______________ of electrons into our out of the needle. Once an excess of electrons is present in the needle, the _____________ charges present in the leaves or needle will repel one another causing the needle to ____________. Whenever a deflection of the leaves or needle is observed, once can deduce that an excess of ________________ is present.

conductor, movement, like, deflect, charge

Materials that readily conduct electrons or allow them to move freely

conductors

During any process, the net electric charge of an isolated system remains _______________. The total amount of charge in the system remains ______________. Charge is neither created nor is it destroyed

constant, uncharged

rubbing/friction

different materials end up with opposite charges based on the properties of each material

Some trucks (especially those carrying combustible fuels) have conducting tires while others use strap-like bands attached to the underside of their rig that drag along the ground in an attempt to discharge static electricity. get rid of moisture. build up negative charge. protect them in case they get hit by lightning none of these is correct.

discharge static electricity.

An insulator differs from a conductor in that an insulator has an excess of protons. has an excess of electrons. can become charged and a conductor cannot. allows electrons to move freely within it. does not allow electrons to move freely within it.

does not allow electrons to move freely within it.

the electroscope will become oppositely charged of the _____________ ____________

inducing object

To charge a conductor by induction, you bring a negatively charged _______________ near the conductor. This polarizes the _______________. You then attach a wire to the conductor so that the electrons are able to move to the _____________. You remove the wire and then move the negatively charged ___________ away. The conductor will be left with a net ________________ charge.

insulator, conductor, ground, insulator, positive

Materials that conduct electrons poorly or do not allow them to move freely

insulators

By rubbing objects together, it is possible to move ______________ charges from one object to another. Two insulators of different materials can become _________________ by rubbing; however, if the insulators are made of the ___________ materials, they will not become charged.

negative, charged, same

The process by which an object becomes charged with static electricity is explained in terms of a model of charges in materials. It is assumed ________________ charges are free to move while the _____________ charges stay fixed in place

negative, positive

When an object is electrically charged, an excess number of electrons results in a ______________ charge, or a deficit of electrons results in a ___________ charge. The net charge on the object is given by the number of excess electrons or deficit electrons times the _______________ of a single electron or proton

negative, positive, charge

A metal sphere is connected to ground through a closed switch. A positively charged balloon is then brought near it. The switch is opened and the balloon is taken away. The sphere is now neutral negatively charged positively charged charged, but we cannot know its sign. none of these

negatively charged

What occurs during 'action-at-a-distance' interactions?

objects involved exert forces on each without touching

Only rubbing one side

only charges that side

When the negative charges in a material are displaced relative to the positive charges in the same material and there has been no transfer of charge between the two object we say that the material has become electrically ________________

polarized

When an uncharged object is brought near a charged object, it becomes ________________, with the two sides of the object becoming _______________ charged. This happens because the negative changes in the uncharged object redistributed themselves under the influence of the ____________ exerted on them by the charged object. This causes the area of the uncharged object closest to the charged object to have the _______________ type of charge and so the two ___________

polarized, oppositely, force, opposite, attract

All materials contain both _____________ and negative charges

positive

Balloons X , Y and Z are suspended from strings as shown above. Negatively charged balloon X attracts balloon Y and balloon Y attracts balloon Z. Balloon Z could be... List all that apply. positively charged. negatively charged. neutral.

positively charged. negatively charged. neutral.

Charging by induction

process of charging a conductor without touching it

Electric charge is a property of ______________ and ______________. Protons carry a ______________ charge and electrons carry a _______________ charge.

protons, electrons, positive, negative

Formula to calculate charge

q= n(missing)e q=total net charge n(missing) e= electron charge

When an electroscope is charged, its leaves separate because unlike charges repel. similar charges exert force on each other over a distance. positive charges spread over the metal leaves. magnetic forces spread the metal leaves apart.

similar charges exert force on each other over a distance.

The net electric charge or just net charge of an object is the sum of the electric charges of its constituent particles. Situations in which the net charge is non-zero are referred to as

static electricity

When two charged conductors TOUCH

the charge is split evenly when separated

If a negatively charged rod is brought near a negatively charged electroscope, there will be no effect. the leaves will fall. the leaves will spread farther apart. the electroscope will become positively charged.

the leaves will spread farther apart.

grounding

the process of removing excess charge on an object by means of the transfer of electrons between it and another object of substantial size

A charged object will always attract a nearby, _______________ object regardless of the material of which the uncharged object is made

uncharged

In an _______________ object, there are equal numbers of positive and negative charges so the object has no overall charge

uncharged

electric polarization

when the centers of positive and negative charges shift so that there is more positive charge on one side of a molecule than another