Positive charges cause your hair to stand up on a cold day and can give you a shock when you touch a doorknob, but they also are responsible for holding atoms together. In this lesson, we’ll learn what creates a positive charge and how it interacts with negative charges.
Types of Electric Charge
There are two fundamental types of electric charges in the universe: positive charges and negative charges. If an object is positively charged, it will repel other positively charged objects, and it will attract negatively charged objects.Atoms, which are the basic unit of matter, have a dense nucleus made up of positively charged protons and neutral neutrons. Surrounding the nucleus are negatively charged electrons.
Although electrons are much smaller and lighter than protons, they have the same amount of charge. That means that an equal number of protons and electrons cancel each other out in terms of the total charge of the atom. Because neutrons are neutral (not positively or negatively charged), their number does not affect the total charge at all.The attraction between protons and electrons helps to hold the atom together, but it is possible for there to be an unequal number of protons and electrons. In that case, the atom is said to be charged.
If the number of protons is bigger than the number of electrons, the atom has a net positive charge, and if the number of electrons is bigger than the number of protons, the atom has a net negative charge. This is also what causes larger objects, made up of those charged atoms, to become charged. If an object has a positive charge, that means it has lost some electrons and now has more protons than electrons.
Objects can become charged by contact with other objects. The transfer of charges between objects is called static electricity. One way to make objects become charged is to rub two initially neutral objects together so that electrons are transferred from one to the other.To see how this works for yourself, you can do a quick and easy experiment at home.
First, get a plastic comb or a balloon and then rub your hair with it. What happened? Did your hair stand up and then stick to the balloon? This happens because the plastic of the comb or balloon picks up electrons from your hair. That means that the plastic becomes negatively charged and your hair becomes positively charged because it now has more protons than electrons. Because each piece of hair has the same positive charge, they all repel each other! Your hair is also attracted to the plastic because it has an opposite negative charge, so it will stick to the balloon or comb. This is an example of static electricity.
Conductors and Insulators
An insulator is a material that does not have any freely mobile electrons, so it does not allow charges to flow through it.
This does not mean that an insulator cannot be charged, however. Insulators can hold a charge for a very long time, in fact, because the charge is stuck in one place and cannot easily be transferred to other objects. Some common insulators are plastic, air, glass, and wood.A conductor is a material that allows electric charges to move through it easily, like metals. In a conductor, some electrons are free to move around.
This allows the electric charges to move within the conductor and also be easily transferred to another material. If a conductor is positively charged, the charge will spread out all over the surface and not stay in just one place.Although you may not realize it, your body is actually a conductor, too! Have you ever touched a doorknob on a cold day and gotten a shock? This happened because you picked up extra electrons as your feet moved across the carpet or your clothes moved against furniture or other objects in the house. When you touched the knob (also a metal conductor), those electrons were able to flow from your hand into the knob. This flow of electrons is called current, and it’s what you feel as an electric shock.
Your body is a conductor because it contains a lot of water, which like metals, is a good conductor of electricity.
Inside an atom, there are positive charges and negative charges. Protons are positively charged. Electrons are negatively charged, and neutrons are neutral. For an atom to be charged, it must have a difference in the number of protons and electrons. Large objects also become charged when they have an imbalance in the number of protons and electrons.
If there are more protons than electrons, the object will be positively charged, and if there are more electrons than protons, it will be negatively charged.Charge that is transferred between objects by rubbing them together is called static electricity. Some types of material, called a conductor (metals, water, etc.
), allow electric charges to move through them easily. This flow of electrons is called a current. On the other hand, other materials may be an insulator (plastic, glass, wood, etc.), which does not allow charges to pass through it.