electric current. the rate at which electrical charges flow through a wire or conductor is called...
TRANSCRIPT
Electric Electric CurrentCurrent
Electric Current
• The rate at which electrical The rate at which electrical charges flow through a wire charges flow through a wire or conductor is called or conductor is called electric currenelectric current.t.
Electrical current = charge passing through a given Electrical current = charge passing through a given area / timearea / time
I = I = ΔΔq/q/ΔΔtt
SI Unit = C/s = Amperes (A)SI Unit = C/s = Amperes (A)
Electric CurrentSample Problem
The current in a light bulb is 0.835 A. How long does it take for a total charge of 1.67 C to pass a point in the wire?
I = I = ΔΔq/q/ΔΔtt
ΔΔt = t = ΔΔq/Iq/I = 1.67 C / 0.835 A == 1.67 C / 0.835 A = 2.00 s2.00 s
ΔΔq = 1.67 Cq = 1.67 C I = 0.835 AI = 0.835 A
Electric Current• Charges flow from high voltage
to low voltage.
– A voltage difference is the push that causes charges to move.
– Voltage difference is measured in volts (V).
– For charges to flow, the wire must always be connected in a closed path, or circuit.
Electric field travels at the speed of light, but the charges do not!!!
Drift Velocity: The net velocity of a charge moving in an e- field.
Electric Current
• 2 Types:
1. Direct current (DC)
- Electrical charges move only in one direction.
- Batteries always generates a direct current (why?……fixed voltage difference).
Types of Current
Direct Current
Types of Currents (cont.) 2. Alternating current (AC)
- Electrical charges are constantly changing directions.
- Commonly used in homes and businesses throughout the world.
Why?
More efficient for long-distance electrical charge transmission.
Alternating Current
Sources of electrical current•A dry cell battery produces
a voltage difference – zinc container – carbon suspension rod– causing current to flow
between them.•Example: AA battery
Dry Cell Battery
•A wet cell battery contains two connected plates made of different metals in a conducting solution.
–Example: Car battery
Sources of electrical current (Cont.)
Generators
- Convert mechanical energy to electrical energy.
- Can produce both direct and alternating current.
Sources of electrical current (Cont.)
•Wall sockets have a voltage difference across the two holes of an electrical outlet.
– generator at a power plant provides this voltage difference.
Sources of electrical current (Cont.)