Conductors And Insulators

We differentiate the elements around us on the basis of their physical properties such as malleability, phase, texture, colour, polarity, solubility etc. But as we know, another very important classification of elements is done on the basis of their conductivity of electric charge. If we perform a simple experiment with a battery and a small LED bulb, we will notice that when then the circuit between the battery and the bulb is completed using a plastic or a cotton thread, the bulb doesn’t glow, whereas if we perform the same experiment with the help of a metallic wire such as copper, the bulb starts to glow. This indicates that some of the elements enable the transfer of charge from the battery to the bulbs, while others do not. The basis of classification of such elements is their conductivity. In this section, we will discuss these elements, the conductors and the insulators.

conductors and insulators

Conductors

Conductors are materials that allow free flow of electrons from one particle to another. These are elements which have electric charges in the form of electrons that are comparatively free to move inside the material. When charge is transferred to such an element, it gets distributed across the entire surface of the object, which results in the movement of electrons in the object. The charges transferred to a conductor distribute until the force of repulsion between electrons in areas of excess electrons is decreased to the minimum value. When such an object is brought in contact with another conductor, the charge gets transferred from the first conductor to the other until the overall repulsion due to charge is minimized.  Some of the common example of conductors includes metals such as copper, gold, iron, etc. Graphite, human body and the earth are also good conductors of electricity.

Insulators

Insulators are materials that hinder the free flow of electrons from one particle of the element to another. If we transfer some amount of charge to such an element at any point, the charge remains at the initial location and does not get distributed across the surface. The common process of charging of such elements includes charging by rubbing (for some elements, with the help of suitable materials) and charging by induction. Plastic, wood, glass, etc. are common examples of insulators.

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Practise This Question

If an object made of substance A is rubbed with an object made of substance B, then A becomes positively charged and B becomes negatively charged. If, however, an object made of substance A is rubbed against an object made of substance C, then A become negatively charged. What will happen if an object made of substance B is rubbed against an object made of substance C?