1. Electricity Review

2. Topics covered Characteristics of Dynamic Electricity –Intensity –Resistance –Potential Difference –Energy –Electrical Power –Work Circuit designs

3. Characteristics 1.Intensity A. Definition The number of charges that flow past a given point in 1 second

4. Characteristics B. Units: –The Current Intensity is measured in Amperes (A) C. Formula: –I = q/∆t Where I = Intensity (A) q = Charges (C) ∆t = variation in time (sec) D. In a circuit: A

5. Characteristics 2.Resistance A. Definition The ability to slow down the electrons. The ability of a material to hinder the flow of the electric curent.

6. Characteristics B. Units: –The Resistance is measured in Ohms (Ω) C. Formula: –V = R I Where V = Potential Difference (V) R = Resistance (Ω) I = Intensity (A) D. In a circuit:

7. Characteristics E. Factors affecting resistance –Nature of the substance Better Conductor = Less resistance –Length The shorter, the less resistance –Diameter The fatter, the less resistance –Temperature The colder, the less resistance

8. Characteristics 3.Potential Difference A.Definition The amount of energy transferred between two points in an electrical circuit. V

9. Characteristics B. Units: –The Potential Difference is measured in Volts (V) C. Formula: –V = E/q Where V = Potential Difference (V) E = Electric Energy (J) q = Charge (C) D. In a circuit: V

10. Characteristics 4.Electrical Power A. Definition The amount of work an electrical device can perform per second or how much energy it can transform in a period of time.

11. Characteristics B. Units: –The Electrical Power is measured in Watts (W) C. Formula: –Pe = W/∆t Where Pe = Electrical Power (W) W = Work (J) ∆t = Time Interval (sec) –Pe = V I WherePe = Electrical Power (W) V = Potential Difference (V) I = Intensity (A)

12. Characteristics C. Formula (Continued) –E = Pe∆t WhereE = Electrical Energy (J or kWh) Pe = Electrical Power (Pe) ∆t = Time Interval (sec or hours)

13. Electrical Circuits

14. Types of electrical circuits A.Series circuit Definition: –Circuit that contains only one branch or path for the electrons to follow. Characteristics –If one element is defective, the electricity does not flow –The intensity is the same all around the circuit –The resistance adds up

15. Electrical Circuits B.Parallel circuit Definition –Circuit that contains at least one branch or paths for the electrons to follow. Characteristics –If an element is defective, the elements on that particular branch will stop working only –Resistance is shared (so resistance is lower) –Current intensity adds up

16. Electrical oddities A switch must be closed in order to allow the energy to flow A light will only light up when the electrons complete a full circuit (one side of the power source to another)