Activity 1(a): The wool and balloon do not show attraction. The explanation for this observation is given below:
We know that an atom consists of a central part called nucleus and around the nucleus there are a number of electrons revolving in different orbits. The nucleus contains protons and neutrons. A proton is a positively charged particle while a neutron has no charge. Electrons are negatively charged particles. The magnitude of the charge of an electron is the same as that of a proton. Normally, the number of electrons is equal to the number of protons in an atom. Therefore, an atom is neutral as a whole: the negative charge on electrons cancelling the positive charge on protons. This leads to the conclusion that under ordinary conditions, an atom is neutral. Matter is made up of atoms. Hence a material body is electrically neutral.
From the above explanation we can understand that wool and balloon are electrically neautral. Hence in the above activity wool and balloon do not show any attraction or repulsion.
In activity 1(b) the rubbed balloon and wool attract each other. The reason is that when the wool is rubbed with the balloon, friction between wool and balloon transfer loosely bound elecrons from wool to balloon. Thus wool loses electrons and gets positively charged and the balloon gains electrons and becomes negatively charged.
The electricity developed on objects, when they are rubbed against each other is called frictional electricity or static electricity.
In activity 1 (C) the balloons repel each other. This is due to the repulsion between the same type of charges developed on the balloons due to rubbing.
From activity 1 (b) and 1 (c) we can conclude that objects which have opposite charge attract each other. Objects with similar charges repel each other.
What is the meaning of a positively charged body? When one or more electrons escape from an atom , the number of electrons in that atom becomes less than the number of protons. Therefore, the net charge of the atom becomes positive. Thus a positively charged body has deficiency of electrons in the body as compared to its neutral state and a negatively charged body has excess of electrons.
We know that an atom consists of a central part called nucleus and around the nucleus there are a number of electrons revolving in different orbits. The nucleus contains protons and neutrons. A proton is a positively charged particle while a neutron has no charge. Electrons are negatively charged particles. The magnitude of the charge of an electron is the same as that of a proton. Normally, the number of electrons is equal to the number of protons in an atom. Therefore, an atom is neutral as a whole: the negative charge on electrons cancelling the positive charge on protons. This leads to the conclusion that under ordinary conditions, an atom is neutral. Matter is made up of atoms. Hence a material body is electrically neutral.
From the above explanation we can understand that wool and balloon are electrically neautral. Hence in the above activity wool and balloon do not show any attraction or repulsion.
In activity 1(b) the rubbed balloon and wool attract each other. The reason is that when the wool is rubbed with the balloon, friction between wool and balloon transfer loosely bound elecrons from wool to balloon. Thus wool loses electrons and gets positively charged and the balloon gains electrons and becomes negatively charged.
The electricity developed on objects, when they are rubbed against each other is called frictional electricity or static electricity.
In activity 1 (C) the balloons repel each other. This is due to the repulsion between the same type of charges developed on the balloons due to rubbing.
From activity 1 (b) and 1 (c) we can conclude that objects which have opposite charge attract each other. Objects with similar charges repel each other.
What is the meaning of a positively charged body? When one or more electrons escape from an atom , the number of electrons in that atom becomes less than the number of protons. Therefore, the net charge of the atom becomes positive. Thus a positively charged body has deficiency of electrons in the body as compared to its neutral state and a negatively charged body has excess of electrons.
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