Why does a neutral hard rubber rod become negatively charged when rubbed with wool?

When a hard rubber rod is given a negative charge by rubbing it with wool:A) Positive charges are transferred from rod to wool.B) Negative charges are transferred from rod to wool.C) Positive charges are transferred from wool to rod.D) Negative charges are transferred from wool to rodE) Negative charges are created and stored on the rod.

Answer

Hint:When a rubber rod is rubbed with fur or felt electrons are transferred from the material to the rod, giving the rod a negative charge. Two negatively charged objects repel. When a positively charged object is brought near a negatively charged object the two objects attract one another. Hence we can choose from the option using the above concept.

Complete step by step solution:
The easiest way to obtain an electric charge is to take any two materials and rub them together. It is noted that one of the materials becomes negatively charged and the other positively charged. For example, if we rub a hard rubber rod with a woolen cloth, the rubber rod acquires a negative charge and the wool an equal amount of positive charge. The charge we call negative is a matter of convention, but with the proposed convention here it is the rubber that becomes negative.
It is known that all matter contains positive and negative charges. The positive charge is very deep inside each atom on the atomic nucleus, while the negative charge is on the electrons that orbit outside the nucleus. Normally, in neutral matter the amounts of positive and negative charges are equal, and we are unaware of either. Given any two materials, it usually happens that one has a greater attraction towards electrons than the other; when the two are rubbed together, the material with higher affinity arrests a few electrons from the material with lower affinity. For example, rubber has a higher electron affinity than wool; when they are rubbed together the rubber captures a few electrons from the wool; the rubber, therefore, obtains an excess of electrons and is negatively charged, while the wool is left with fewer electrons and is positively charged.

Hence, Option D is correct.

Note:In Positively charged particles, the number of positive ions is more than the number of negative ions. This means that the number of protons is more than the number of electrons. To neutralize positively charged particles, electrons from the locality come to this article until the number of protons and electrons become equal. Similarly, negatively charged particles' number of electrons is larger than the number of protons. To neutralize negatively charged particles, because protons cannot move and cannot reach negatively charged particles, electrons move to the ground or any other particle around. In neutral particles, it involves an equal number of protons and electrons. They have both protons, neutrons, and electrons but the number of positive ions is equal to the number of negative ions.

Suppose that a rubber balloon is rubbed with a sample of animal fur. During the rubbing process, the atoms of the rubber are forced into close proximity with the atoms of the animal fur. The electron clouds of the two types of atoms are pressed together and are brought closer to the nuclei of the other atoms. The protons in the atoms of one material begin to interact with the electrons present on the other material. Amidst the sound of crackling air, you might even be able to hear the atoms saying, "I like your electrons." And of course, the atoms of one material - in this case, the atoms of rubber - are more serious about their claim for electrons. As such, the atoms of rubber begin to take electrons from the atoms of animal fur. When the rubbing has ceased, the two objects have become charged.

The procedure of rubbing a rubber balloon against your hair is quite easily performed. You might try it now if you've never performed it. When done, you will likely notice that the rubber balloon and your

How Triboelectric Charging Works

The triboelectic charging process (a.k.a., charging by friction) results in a transfer of electrons between the two objects that are rubbed together. Rubber has a much greater attraction for electrons than animal fur. As a result, the atoms of rubber pull electrons from the atoms of animal fur, leaving both objects with an imbalance of charge. The rubber balloon has an excess of electrons and the animal fur has a shortage of electrons. Having an excess of electrons, the rubber balloon is charged negatively. Similarly, the shortage of electrons on the animal fur leaves it with a positive charge. The two objects have become charged with opposite types of charges as a result of the transfer of electrons from the least electron-loving material to the most electron-loving material.

Triboelectic charging is often demonstrated in Physics class. Two rubber balloons can be suspended from the ceiling and hung at approximately head height. When rubbed upon a teacher's head, the balloons became charged as electrons are transferred from the teacher's fur to the balloons. Since the teacher's fur lost electrons, it became positively charged and the subsequent attraction between the two rubbed objects could be observed. Of course, when the teacher pulls away from the balloons, the balloons experienced a repulsive interaction for each other.

The Law of Conservation of Charge

The triboelectic charging process (as well as any charging process) involves a transfer of electrons between two objects. Charge is not created from nothing. The appearance of negative charge upon a rubber balloon is merely the result of its acquisition of electrons. And these electrons must come from somewhere; in this case, from the object it was rubbed against. Electrons are transferred in any charging process. In the case of triboelectic charging, they are transferred between the two objects being rubbed together. Prior to the charging, both objects are electrically neutral. The net charge of the system is 0 units. After the charging process, the more electron-loving object may acquire a charge of -12 units; the other object acquires a charge of +12 units. Overall, the system of two objects has a net charge of 0 units. Whenever a quantity like charge (or momentum or energy or matter) is observed to be the same prior to and after the completion of a given process, we say that the quantity is conserved. Charge is always conserved. When all objects involved are considered prior to and after a given process, we notice that the total amount of charge amidst the objects is the same before the process starts as it is after the process ends. This is referred to as the law of conservation of charge.

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

1. During a physics lab, a plastic strip was rubbed with cotton and became positively charged. The correct explanation for why the plastic strip becomes positively charged is that ...

a. the plastic strip acquired extra protons from the cotton.

b. the plastic strip acquired extra protons during the charging process.

c. protons were created as the result of the charging process.

d. the plastic strip lost electrons to the cotton during the charging process.

2. Saran Wrap has a larger electron affinity than Nylon. If Nylon is rubbed against Saran Wrap, which would end up with the excess negative charge? ____________ Explain.

3. A physics teacher rubs a glass object and a felt cloth together and the glass becomes positively charged. Which of the following statements are true? Circle all that apply.

a. The glass gained protons during the rubbing process.

b. The felt became charged negatively during this rubbing process.

c. Charge is created during the rubbing process; it is grabbed by the more charge-hungry object.

d. If the glass acquired a charge of +5 units, then the felt acquires a charge of -5 units.

e. This event violates the law of conservation of charge.

f. Electrons are transferred from glass to felt; protons are transferred from felt to glass.

g. Once charged in this manner, the glass object and the felt cloth should attract each other.

h. In general, glass materials must have a greater affinity for electrons than felt materials.

4. Which statement best explains why a rubber rod becomes negatively charged when rubbed with fur?

a. The rubber that the rod is made of is a better insulator than fur.

b. The fur is a better insulator than the rubber.

c. Molecules in the rubber rod have a stronger attraction for electrons than the molecules in the fur.

d. Molecules in the fur have a stronger attraction for electrons than the molecules in the rubber rod.

Why will a rubber rod rubbed with wool repel a negatively charged ball?

Why a rubber rod becomes negatively charged when rubbed with fur?

Why does an object become negatively charged when rubbed?

When a rubber rod is rubbed with wool the rod becomes negatively charged what can you conclude about magnitude of charge on wool and rubber rod Why?