Electric charge

✏️ Check What You Know: Electric Charge Quiz

Do you really know what an electric charge is and where it comes from? Take the 10-question quiz to find out. You won’t need paper or a pencil. Every answer is explained, and each time you play you get a new mix of questions.

⚛️ What Is an Electric Charge?

Before showing you what an electric charge is, a discussion of what electrical forces are is important. Keep reading carefully! In the end, you will know why your finger received an electric shock when you touch a door handle.

Beside the force of gravity acting on you, imagine also another pair of forces that are very powerful acting on you called electrical attracting force and electrical repelling force.

See the electrical attracting force as coming from the earth and the electrical repelling force as coming from your body.

Why don't you feel the effect of this pair of forces? You don't feel anything because the two forces balance each other.

In the end, you only feel the force of gravity.

Now that you are aware of the presence of electrical forces, where do these forces come from?

Electrical forces come from particles in atoms. Particles in atoms are called electrons, protons, and neutrons.

The model of an oxygen atom is shown below.

In an oxygen atom, there are 8 protons, 8 neutrons, and 8 electrons.

The 8 protons and 8 neutrons form what we call the nucleus.

The nucleus is surrounded by electrons and the electrons are shown in red.

Although it is not clearly shown on the picture above, the mass of a proton is far greater than that of an electron. The mass of a proton is almost 2000 times the mass of an electron.

It is commonly accepted that an electron carries a negative charge and a proton carries a positive charge. The charge of an electron is equal in magnitude to the charge of a proton.

The protons attract the electrons and hold them in orbit. However, electrons repel other electrons.

Basically, opposite charges attract, but like charges repel.

Under normal conditions, there are as many electrons as protons in an atom. We say that the atom has a zero net charge.

If an atom happens to have more electrons or more protons, we call this phenomenon charge or electric charge.

If the number of electrons exceeds the number of protons, the atom is negatively charged.

On the other hand, if the number of protons exceeds the number of electrons, the atom is positively charged.

🔋 Conservation of electric charge

A neutral atom is an atom that has the same number of electrons as protons.

In the atom shown above, the 2 innermost negatively charged electrons are attracted a lot to the positively charged nucleus. However, it is not the same for the other 6 outermost electrons. They can easily be cut loose by outside forces.

If an electron is removed or lost, the atom is no longer neutral, it is electrically charged.

Rubber does not easily lose its electrons while this happens a lot easier with silk or human skin. We say that rubber has more electron affinity.

This happened because your body was not neutral, but negatively charged and the door handle was positively charged with fewer electrons.

The door handle wanted the extra electron(s) from your body.

As the extra electrons transferred from your body to the door handle, you experienced a tiny shock. This is an example of static electricity or electricity at rest since no wires are involved here.

When an atom is electrically charged, the atom has a net charge. An atom that is electrically charged is called an ion. A positive ion has a net positive charge while a negative ion has a net negative charge.

Whenever objects carry a net positive or negative charge, there is an imbalance in electrical charge. As a result, electrical forces will arise that will cause objects with this imbalance to either attract or repel each other.

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