1. An atom is charged if there is an imbalance between the number of protons and electrons.
2. A positive charge is generated when there are less electrons than protons. 3. A negative charge is generated when there are more electrons than protons. 4. Static electricity is generated when an object becomes charged. 5. Electric discharge is the rapid transfer of electrons from one object to another. 6. Current electricity is the steady flow of charge through a conductor. 7. Potential difference or voltage is the difference between the electric potential at two points in a circuit and is measured in volts (V).
8. Electric current is the flow of electric charge and is measured in amps (A). 9. Resistance (R) is the opposition to the flow of electrons in a circuit and is measured in ohms (Ω).
10. Electrical circuits can be represented using circuit diagrams. 11. In a series circuit there is only one path along which electrons can flow. 12. In a parallel circuit there is more than one path along which electrons can flow. 13. Ohm’s Law states that when the temperature is constant the amount of steady current (I) passing through a material is directly proportional to the voltage (V) across the material:
V I
= R
14. Electrical power (P) is the rate at which electrical energy is either produced or consumed and is measured in watts. P = IV.
Questions and Exercises K C
Key Concepts Rewrite the following sentences in your copybook and fill in the blanks. All matter is made of ___________. ___________ can be added or removed from atoms. If there are more ___________ than ___________ the atom has a positive charge. If there are more ___________ than ___________ the atom has a negative charge. Objects that are charged are said to have ___________ ___________. ___________ is a form of electric discharge. The steady ___________ of electric charge through a ___________ is called ___________ electricity. A ___________ is an object that allows electric charge to flow through it. ___________ is an example of an electrical conductor. ___________ is an example of an electrical insulator. Electric ___________ is the ability to move electrons. ___________ ___________ is the difference between the electric potential at two points in a circuit.
