1. Electric Current
6.2

2. Current and Voltage Difference
Electric Current-The net movement of electric charge in a single direction.
Measured in Amperes (A)
One Ampere is equal to 1 coulomb per second
If there is no current, there is no NET movement
Movement forward=movement backward=movement side-to-side
When an electric current is applied, there is still backward and forward movement, but the electrons drift in the direction of the current.
Net movement

3. Before Current is Applied
After Current is Applied

4. Current and Voltage Difference
Related to the force that causes electric charges to flow.
From area of high voltage to low voltage
Measured in volts (V)
Electric Circuits
A closed path that electric current follows
Battery, wire, lightbulb
Current and electron flow
For historical reasons, we think of current as flow of positive charges
Positive charges do not flow
Due to this, current is in the opposite direction of electron flow
Electrons flow from lower to higher voltage
Current is from higher to lower voltage

7. Batteries
2 Main Types:
Dry-cell
Wet-cell

8. Dry-Cell Batteries Carbon Rod (positive) Zinc Container (negative)
Moist paste (electrolyte)
Allows electrons to flow
Batteries in flashlights
Metals can be different
Lithium, carbon, and lithium
solution
Cell phone battery

9. Wet-cell Battery
2 connected plates made of different metals in an electrolyte
Unlike the paste in dry-cells, the wet-cell has a liquid
Has many cells connected together.
Most common type is lead-acid
Lead and Lead dioxide in sulfuric acid solution

10. Electrical Outlets The 2 holes of an outlet have a voltage difference
In the U.S. usually 120 V

11. Resistance Tendency of object to resist flow of electrons
Takes some of the flowing electrons from the current
Measured in ohms (Ω)
This symbol is the capital form of the Greek letter “Omega”
This is why batteries charging get warm
The resistor is taking some of the electrons, and converts the chemical energy to thermal energy

12. Ohm’s Law Current(A)=Voltage difference(V)/resistance(Ω) 𝐼= 𝑉 𝑅
Current is measured in Amps (A)
𝐼= 𝑉 𝑅
Where I is current

13. Example Problem
The voltage difference in a graphing calculator is 6V, and the resistance is 1,200 Ω. What is the current through the batteries of the graphing calculator?
Knowns: V=6V, R=1200 Ω
Unknown: I=?
Equation: 𝐼= 𝑉 𝑅
Solve: 𝐼= 𝑉 𝑅 = 6𝑉 1200Ω
=0.005 A

14. Equations
Solve for V
Solve for R

15. Guided Practice
An object has a resistance of 60 Ω as a current of 2 A goes through it. What is the voltage difference across the object?

16. You Try It!
The voltage in a device is 50 V, and the resistance is 5 Ω. What is the current in the device?

17. Types of Current Alternating Current (AC) Direct Current (DC)
Type found in household electrical outlets
Changes direction
Direct Current (DC)
Found in battery-powered devices
Does not change direction
Converters change types (ACDC)