What causes an object to have a positive charge?

Charge Interactions

Suppose that you rubbed a airship with a sample of animal fur such as a wool sweater or even your own hair. The balloon would likely become charged and its charge would exert a foreign influence upon other objects in its vicinity. If some small $.25 of paper were placed upon a table and the balloon were brought most and held in a higher place the newspaper $.25, then the presence of the charged balloon might create a sufficient attraction for the newspaper $.25 to heighten them off the table. This influence - known every bit an electrical forcefulness - occurs even when the charged balloon is held some distance abroad from the paper $.25. The electric force is a non-contact force. Any charged object can exert this strength upon other objects - both charged and uncharged objects. One goal of this unit of The Physics Classroom is to understand the nature of the electric strength. In this part of Lesson one, ii unproblematic and fundamental statements will be made and explained near the nature of the electric strength.

Perhaps you have heard it said then many times that it sounds like a cliche.

Opposites concenter. And likes repel.

These two central principles of accuse interactions will be used throughout the unit to explicate the vast array of static electricity phenomena. As mentioned in the previous section of Lesson i, there are two types of electrically charged objects - those that incorporate more protons than electrons and are said to be positively charged and those that contain less protons than electrons and are said to exist negatively charged. These two types of electrical charges - positive and negative - are said to be opposite types of charge. And consistent with our fundamental principle of charge interaction, a positively charged object volition attract a negatively charged object. Oppositely charged objects will exert an bonny influence upon each other. In contrast to the attractive strength betwixt two objects with opposite charges, two objects that are of like charge volition repel each other. That is, a positively charged object volition exert a repulsive force upon a second positively charged object. This repulsive force will push the two objects autonomously. Similarly, a negatively charged object will exert a repulsive force upon a 2d negatively charged object. Objects with like charge repel each other.

The Electric Strength and Newton's Third Law

This electric force exerted betwixt ii oppositely charged objects or two like charged objects is a force in the same sense that friction, tension, gravity and air resistance are forces. And beingness a forcefulness, the same laws and principles that describe any force describe the electrical force. One of those laws was Newton'south police of activeness-reaction (discussed in Unit 2 of The Physics Classroom). According to Newton's third law, a force is simply a mutual interaction between two objects that results in an equal and opposite push button or pull upon those objects. Let's apply Newton'due south third constabulary to describe the interaction betwixt Object A and Object B, both having positive charge.

Object A exerts a rightward push upon Object B. Object B exerts a leftward push upon Object A. Encounter diagram at right. These ii pushing forces have equal magnitudes and are exerted in opposite directions of each other. Each object does its own pushing upon the other. The push upon Object B (by Object A) is directed away from Object A; and the push upon Object A (by Object B) is directed abroad from Object B. Because of the away from nature of the common interaction, the force is said to be repulsive .

At present let's apply the same action-reaction principle to ii oppositely charged objects - Object C (positive) and Object D (negative). See diagram at right. Object C exerts a leftward pull upon object D. Object D exerts a rightward pull upon Object C. Again, each object does its ain pulling of the other. Just as earlier, these two forces take equal magnitudes and are exerted in opposite directions of each other. However in this instance, the direction of the forcefulness on Object D is towards Object C and the management of the force on Object C is towards object D. Because of the towards each other nature of the mutual interaction, the strength is described as being attractive .

Interaction Between Charged and Neutral Objects

The interaction betwixt two like-charged objects is repulsive. The interaction betwixt two oppositely charged objects is attractive. What blazon of interaction is observed between a charged object and a neutral object? The respond is quite surprising to many students of physics. Any charged object - whether positively charged or negatively charged - will have an bonny interaction with a neutral object. Positively charged objects and neutral objects attract each other; and negatively charged objects and neutral objects attract each other.

This third interaction betwixt charged and neutral objects is often demonstrated by physics teachers or experienced by students in physics lab activities. For case, if a charged balloon is held above neutral bits of paper, the forcefulness of attraction for the newspaper bits will be strong enough to overwhelm the downward forcefulness of gravity and raise the bits of paper off the tabular array. If a charged plastic tube is held above some $.25 of newspaper, the tube will exert an bonny influence upon the paper to heighten information technology off the table. And to the bewilderment of many, a charged rubber balloon can exist attracted to a wooden cabinet with plenty forcefulness that it sticks to the cabinet. Whatsoever charged object - plastic, rubber, or aluminum - volition exert an attractive force upon a neutral object. And in accordance with Newton's police of action-reaction, the neutral object attracts the charged object.

Flickr Physics Photo

A balloon is charged past rubbing information technology with hair. It is and then brought near some bits of paper. The charged balloon attracts the newspaper bits, lifting them up off the table. This demonstrates the allure between charged objects and neutral objects.

Repulsion versus Attraction

Because charged objects interact with their environment, an observed interaction provides possible evidence that an object is charged. Suppose that yous enter the physics classroom and discover two balloons suspended from the ceiling. Rather than hanging straight down vertically, the balloons are hanging at an angle, exhibiting a repulsive interaction as shown at the right. The only way that 2 objects can repel each other is if they are both charged with the same type of charge. Thus, the repulsion of the balloons provides conclusive testify that both balloons are charged and charged with the same blazon of charge. 1 could not conclude that the balloons are both positively charged or both negatively charged. Boosted information or further testing would be required to brand a determination about the type of excess accuse present upon the balloons. Nonetheless, one can be convinced that both balloons possess an excess charge - either positive or negative.

Now let's contrast the observation of repulsion with that of allure. Suppose that you now enter the physics classroom and discover 2 balloons suspended from the ceiling and exhibiting an bonny interaction as shown at the right. At that place are two underlying reasons for two objects attracting each other. 1 balloon could be neutral and the other balloon charged or both balloons could be charged with the reverse type of charge. Thus, your only decision could be that at least i of the balloons is charged. The other airship is either neutral or charged with the reverse type of accuse. You cannot draw a determination nigh which ane of the balloons is charged or what type of accuse (positive or negative) the charged balloon possesses. Additional data or farther testing would be required to brand these conclusions. For instance, if you could take each balloon and individually bring them near some neutral bits of paper, you could test to see if each individual balloon is charged or neutral. If a balloon were charged, and so information technology would exhibit an attractive interaction with the neutral paper $.25. On the other hand, an uncharged balloon would non interact at all with neutral newspaper bits.

The to a higher place idea experiments illustrate the conclusive nature of a repulsive interaction. When objects repel each other, 1 tin be sure that both objects are charged. On the other had, the observation of an attractive interaction leads to express conclusions. At best, one can conclude that at least 1 of the objects is charged.

We'll conclude this part of Lesson 1 by asking the question "How can a charged object and a neutral object attract?" As yous've read this page, you lot might have been thinking something like "But I've merely heard of two cardinal accuse interactions - opposites concenter and likes repel. Where did this third charge interaction come from?"

In all likelihood, most of us have only heard of ii types of charge interactions (opposites concenter and likes repel); and both of these charge interactions are fundamental interactions. The third statement - whatever charged object and a neutral object will attract each other - is simply an observable fact that can be explained by the two key accuse interactions. How? The caption of this 3rd accuse interaction volition be saved for the concluding page of Lesson ane. Just first, the subject of conductors and insulators must be explored in order to empathise our third type of charge interaction.

Flickr Physics Photo

Two like-charged balloons hang from a common bespeak from the ceiling. The repulsion effects cause them to hang at an angle from their usual vertical alignment. A plastic tube is charged by rubbing with synthetic fur. The plastic tube is inserted into the infinite betwixt the balloons, causing fifty-fifty further repulsion.

We Would Similar to Suggest ...

Sometimes it isn't enough to simply read about information technology. You have to interact with it! And that's exactly what you lot practice when you utilise 1 of The Physics Classroom'southward Interactives. We would like to advise that you combine the reading of this page with the apply of our Charging Interactive. Y'all can find it in the Physics Interactives department of our website. The Charging Interactive is an electrostatics "playground" that allows a learner to investigate a variety of concepts related to charge, charge interactions, charging processes, and grounding. Once you become the hang of the concepts, put your game-confront on tap the Play button.

Bank check Your Understanding

Apply your understanding of charge to answer the following questions. When finished, click the push to view the answers.

1. Electrical forces ____.

a. tin can cause objects to simply concenter each other

b. can cause objects to simply repel each other

c. tin can cause objects to concenter or repel each other

d. have no effect on objects

ii. On two occasions, the following charge interactions betwixt balloons A, B and C are observed. In each case, it is known that balloon B is charged negatively. Based on these observations, what can you conclusively confirm about the accuse on airship A and C for each situation.

3. Upon entering the room, you detect 2 balloons suspended from the ceiling. You notice that instead of hanging straight down vertically, the balloons seems to be repelling each other. You tin conclusively say ...

a. both balloons have a negative charge.

b. both balloons have a positive charge.

c. ane airship is charge positively and the other negatively.

d. both balloons are charged with the aforementioned type of charge.

Explain your reply.

four. Jean Yuss is investigating the charge on several objects and makes the following findings.

Object C	Object D	Object E	Object F
attracts B	repels C	attracts D repels F	attracts A

Jean knows that object A is negatively charged and object B is electrically neutral. What tin can Jean Yuss definitively conclude near the charge on objects C, D, East, and F? Explain.

six. Two objects are charged as shown at the right. Object X will ____ object Y.

a. concenter

b. repel

c. non impact

7. Ii objects are shown at the right. 1 is neutral and the other is negative. Object 10 will ____ object Y.

a. attract

b. repel

c. non affect

8. Balloons 10 , Y and Z are suspended from strings as shown at the right. Negatively charged balloon X attracts airship Y and balloon Y attracts balloon Z. Airship Z ____. List all that apply.

a. may be positively charged

b. may exist negatively charged

c. may exist neutral

d. must be positively charged

e. must be negatively charged

f. must be neutral

(Notation: This is an practise in logic and reasoning as much as information technology is an do in physics.)

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Source: https://www.physicsclassroom.com/class/estatics/Lesson-1/Charge-Interactions

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