GED Science Practice Test: Electrical Charge

In order to understand electricity, we must understand electrical charge.  If you think back to the chemistry unit on atom structure, you will remember that atoms are made up of a nucleus with positively-charged protons and neutral neutrons, and an electron cloud made up of fast moving, small, negatively-charged electrons. Protons and neutrons, then, have opposite charges. Thus, an atom with equal numbers of protons and electrons is described as being electrically neutral. On the other hand, if an atom has an unequal number of protons and electrons, then the atom is electrically charged (and called an “ion.”)  An atom that has more protons than electrons is said to be a positively-charged ion, while an atom with more electrons than protons is said to be a negatively-charged ion.

In fact, atoms are not the only thing that are capable of having an electrical charge. Molecules and even whole objects can be described as positively- or negatively-charged.

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As you continue to study electricity in this lesson, it is useful to remember that opposite charges attract each other, and like charges repel each other.  For example, positive and negative charges are attracted to each other (this is how negatively-charged electrons remain in an atom, because they are attracted to the positively-charged protons in the nucleus).  Alternatively, negative and negative charges repel each other, just as positive and positive charges repel each other.  Objects with no charge neither attract nor repel each other.

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