This creates a repellent force as shown in the illustration. The same occurs with two negative charges, because their respective forces also act in opposite directions. The electric field and resulting forces produced by two electrical charges of the same polarity. The two charges repel each other. If a positive charge and a negative charge interact, their forces act in the same direction, from the positive to the negative charge.
The interaction between two oppositely charged objects is attractive. What type of interaction is observed between a charged object and a neutral object? The answer is quite surprising to many students of physics. Any charged object - whether positively charged or negatively charged - will have an attractive 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 between charged and neutral objects is often demonstrated by physics teachers or experienced by students in physics lab activities. For instance, if a charged balloon is held above neutral bits of paper, the force of attraction for the paper bits will be strong enough to overwhelm the downward force of gravity and raise the bits of paper off the table. If a charged plastic tube is held above some bits of paper, the tube will exert an attractive influence upon the paper to raise it off the table.
And to the bewilderment of many, a charged rubber balloon can be attracted to a wooden cabinet with enough force that it sticks to the cabinet. Any charged object - plastic, rubber, or aluminum - will exert an attractive force upon a neutral object. And in accordance with Newton's law of action-reaction , the neutral object attracts the charged object.
Because charged objects interact with their surroundings, an observed interaction provides possible evidence that an object is charged. Suppose that you enter the physics classroom and observe 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 two 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 evidence that both balloons are charged and charged with the same type of charge. One could not conclude that the balloons are both positively charged or both negatively charged. Additional information or further testing would be required to make a conclusion about the type of excess charge 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 attraction.
Suppose that you now enter the physics classroom and observe two balloons suspended from the ceiling and exhibiting an attractive interaction as shown at the right. There are two underlying reasons for two objects attracting each other.
One balloon could be neutral and the other balloon charged or both balloons could be charged with the opposite type of charge. Thus, your only conclusion could be that at least one of the balloons is charged. The other balloon is either neutral or charged with the opposite type of charge. You cannot draw a conclusion about which one of the balloons is charged or what type of charge positive or negative the charged balloon possesses. Additional information or further testing would be required to make these conclusions.
For example, 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, then it would exhibit an attractive interaction with the neutral paper bits. On the other hand, an uncharged balloon would not interact at all with neutral paper bits. The above thought experiments illustrate the conclusive nature of a repulsive interaction. When objects repel each other, one can be certain that both objects are charged.
On the other had, the observation of an attractive interaction leads to limited conclusions. At best, one can conclude that at least one 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?
Where did this third charge interaction come from? In all likelihood, most of us have only heard of two types of charge interactions opposites attract and likes repel ; and both of these charge interactions are fundamental interactions. The third statement - any charged object and a neutral object will attract each other - is simply an observable fact that can be explained by the two fundamental charge interactions.
The explanation of this third charge interaction will be saved for the last page of Lesson 1. But first, the subject of conductors and insulators must be explored in order to understand our third type of charge interaction. Use your understanding of charge to answer the following questions. Learn more. Ask Question. Asked 8 years ago. Active 2 years, 4 months ago. Viewed k times. Improve this question. Volker Siegel 3, 1 1 gold badge 21 21 silver badges 55 55 bronze badges.
Muhammad Umer Muhammad Umer 2, 6 6 gold badges 19 19 silver badges 22 22 bronze badges. You can find arbitrarily large sets of charges that are repulsive in all possible pairing, but you can not find a similar set of more than two charges that are attractive in all possible pairing.
That implies that the sets of mutually repulsive charges are all the same, while mutually attractive charges are distinct. Add a comment. Active Oldest Votes. Improve this answer. JMac Michael Michael I don't keep up on these things. With this Lagrangian in hand and adding in a free-particle Lagrangian , it seems to me that one can deduce Coulomb's law without resort to anything quantum.
But it is QM that tells you to look for unitary representations of the Poincare group in the first place. Remember pair production was necessary to rescue the uncertainty principle. A classical theory is perfectly happy to live without it. Is their repelsion actually the result of the attraction of the opposite charges? In other words, if we look at this picture i.
Show 1 more comment. Scientific revolutions occur when we have to change the model, i. Your last paragraph should be on our dashboard to respond to the multiple "why" questions that appear weekly although Michael' answer is nice, too.
I might ask why an apple falls out of the tree in the first place, and my intent might be to find deeper truths about that fact, like the fact that the Earth exerts a gravitational field that pulls the apple down.
I think that's the kind of a "why" that the OP is offering here. It is not the model that creates the charges. The charges exist and the mathematics of the model reproduces the existing behavior.
Mathematics in physics describes "how", not "why". The other way around, "mathematics creates reality" is the platonic view. I am an experimentalist, therefore I stress that reality exists, and mathematical models model it. I first met field theory in a model of nuclear physics back in I cannot take fields as a fundamental explanation of reality.
There already is another proposed layer , the mathematics of strings. Who knows what the theory of everything will be years from now? Each generation believes it was found :. Have you looked at the amplituhedron en. Even though he used the quantum in his photo electric effect paper, and really established the reality that energy is quantized; he generally was opposed to quantum mechanics for many years.
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