Physics Electricity

Electric Charges Everything in the universe is either matter or energy. We studied matter in the Chemistry unit; it is everything that we can touch, smell, taste, and see. Energy is the ability to do work and it comes in many different forms. Forms of energy include: kinetic energy (energy of movement), light, heat, solar energy (from the Sun), geothermal energy (from the Earth), hydro power (from water falling through turbines), wind, and electricity.

Do you remember what three particles make up an atom? In order to study electricity, we have to take one more look at matter. Do you remember what three particles make up an atom? Protons, electrons, and neutrons. Protons and neutrons are in the nucleus (center core) of the atom while electrons spin in energy levels (called orbits or shells) around the nucleus. Since electrons are not firmly held to the nucleus, they have the ability to leave atoms. When electrons leave atoms, matter becomes charged. When electrons are made to flow, electricity is generated.

There are two types of electricity: static electricity and current electricity. The study of static electricity is called electrostatics. Static electricity is when objects become charged. The charges on these objects do not flow from one object to the other. Objects become charged when they are rubbed together. When two objects are rubbed together, electrons can jump from one object to the other. Current electricity is the type of electricity you are familiar with; this is when electricity flows through a specific path (called a circuit) that is usually made up of wires. This is the type of electricity that powers electrical devices such as appliances.

Types of Charges Objects can exist in three different charged states: positively charged, negatively charged, or neutral (no charge). Objects can only lose electrons. Atoms are unable to lose protons because they are held very tightly within the atom’s nucleus. When two objects are rubbed together, electrons will leave one object and the other object will gain those electrons. Therefore, every time objects are rubbed together, one will become positive and the other will become negative (since one must lose electrons and the other must gain electrons).

The Law of Electric Charges The Law of Electric Charges states that objects with the same charge (for example, two negatively charged objects) will always repel (move away from) each other while objects with different charges will always be attracted (move towards) each other. Like charges repel, unlike charges attract. Neutral objects will always be attracted to positively or negatively charged objects as well. Neutral objects will never be attracted or repelled from other neutral objects.

A neutral object will always have the same number of protons and electrons If an object is positively charged that means that they have more protons than electrons If an object is negatively charged that means that they have more electrons than protons Complete Worksheet Part A now

Worksheet Part A Repulsion Attraction Replusion

Understanding the Law of Electric Charges can also help you determine the charge of unknown objects. Complete Part B of the worksheet on the back page

Worksheet Part B Positive or Neutral Negative Negative or Neutral Negative or Positive Neutral

Static and Current Electricity Once again, static electricity is when an object becomes charged (by gaining or losing electrons) from rubbing against another object. Static electricity does not move. Current electricity is when electricity (or electrons) flow. Current electricity travels along a path (known as a circuit) from where the electricity is generated. For example, electricity in most of Ontario flows from Niagara Falls (where electricity is generated after water falls through turbines and powers generators) through power lines (like the ones you see in large hydro towers) to people all over Ontario.

Law of Electric Charges Worksheet Homework