Dynamic Electricity Flashcards
TWO TYPES OF ELECTRICITY
Static and dynamic
Static electricity
Static electricity is when you charge an object, and it repels or attracts other charged (or neutral) objects
Dynamic electricity
Current electricity the flow of electrons within a conducting material.
What can we measure in this Static situation?
Static electricity has a limited number of measurable variables:
1) number of electrons transferred ,
2) amount and sign of charge on the object (measured in C),
3) amount and type of electric Force between charged objects
(measured in N)
What could we measure in a
Dynamic Electricity system?
The movement of electrons (dynamic electricity) introduces new quantities to measure, for example:
the rate of electron flow (how much charge per second is travelling in the wire), the “pressure” pushing the electrons through the wire (voltage/potential difference),
the resistance to electron flow, etc.
Power source
Power source: Source of energy used to move electrons in a circuit, creates a potential difference compelling the electrons to move.
Example: Battery
Conducting wires
Conducting Wires: Allows electrons to travel from one part of a circuit to another part. Carries the charges pushed by the power supply to the circuit elements, then back to the power supply.
Current
An electric current is the orderly flow of negative charges carried by electrons
The conventional direction of a current is from the positive terminal of a power supply towards the negative terminal. (This is opposite of Electron Flow.)
(Think back to our electric field drawings from static electricity: FROM positive TO negative!)
Circuit elements
Circuit Element(s): these items resist the flow of electrons and consume energy/voltage available to the circuit when they perform their tasks.
Ex: light bulb – converts electrical energy to light and heat
Open VS Closed circuit. What does it depend on?
Circuit functions depend on the flow of electrons.
If something prevents electrons from flowing (switch, broken wire, etc) ALL electron movement stops.
Open circuit = OFF, Closed circuit = ON
*Electrons cannot flow if they do not have a path back to their source
Current intensity
The Current Intensity measures how much charge per second is moving through the circuit at a particular point.
It is similar to the intensity of traffic flow on a highway, or water flow in a pipe or hose. per second
Greater intensity =
Greater intensity = more electrons are flowing
Direct Current (DC
Electrons travel through the conductors from one end to the other, pushed by the potential difference (voltage) of the DC power source (ex: battery).
Most electronic devices function on DC current. The “box” on power adaptors converts the AC current from the wall outlet to DC current for the electronic device.
Alternating current (AC)
Alternating Current (AC) – Electrons “wiggle” back and forth. This “wiggling” is caused by the AC power source. The motion is communicated from electron to neighboring electron all along the wire.
Power generating stations produce AC current. AC current is optimal for sending electricity long distances (DC current has too much loss).
AC current can power motors, heating elements, and other simple mechanical devices.
How do we measure the intensity of a current?
An Ammeter is used to measure the intensity of electric current.
It has to be placed in series (in line) with the circuit branch being measured.
(traffic analogy: to measure the amount of cars moving through the highway, you would install a car detector across the highway lanes)
