1. What do you think? What do you think these four pictures have in common?

2. Electric Current and Electrical Energy  Today, I can describe voltage and its relationship to electric currents.  Describe electric current  Describe voltage and its relationship to electric current

4. Electric Current  measured in amperes (Amps).  The symbol for amps is the letter A  The symbol for electric current is the letter I  The higher the current, the greater the number of charges that pass the point each second

5. 2 Types of Electric Current  Direct Current (DC) in which the charges always flow in the same direction. example: electric current from camera batteries  Alternating Current (AC) in which the charges continually shift from flowing in one direction to flowing in the reverse direction. example: electric current from a wall outlet

6. How does Electric Current flow?

7. Voltage definition : a measure of how much work is needed to move a charge between two points.  measured in volts ( V )  The higher the voltage, the more energy is released per charge, and the greater the current.

8. Resistance definition: the opposition to the flow of electric charge.  “electrical friction”  measured in Ohms ( Ω )  In equations, the symbol is the letter R  An object’s resistance depends on its material, thickness, length, and temperature.  The higher the resistance, the lower the current  If the voltage doesn’t change: as the resistance goes up, the current goes down

9. Resistance and Materials  Good conductors (ex: Cu, copper) have low resistance.  Materials with low resistance are used to make wires.  Poor conductors (ex: Fe, iron), have high resistance.  Insulators have such a high resistance that electric current cannot flow in them.

10. Electrical Current, Voltage, and Resistance

11. Exit Ticket 1. If resistance in a material increases and the voltage across the object is constant, current (increases, decreases). Circle one. 2. Assuming constant voltage, the (higher, lower) the resistance is, the higher the current. Circle one. 3. Resistance depends on an object’s material, thickness, length, and (color, temperature). Circle one. Choose the correct term to complete the following sentences. A. An the rate of flow of electric charges in a circuit. B. In a, the charges always flow in the same direction. C. The opposition presented to the current by a material or device is the. D. The potential difference between two points in a circuit is the. E. Charges continually change direction in an. Word Bank: alternating currentdirect current voltage resistanceelectrical current