EVERYTHING FROM UNIT 3 Flashcards
STATIC CHARGE
Static Charge is static electricity: It is electric charge that stays in the same place until it is lost to other objects or to the air.
What’s it measured in?
It’s measured in coulombs, which is the unit of electric charge.
CHARGED MATERIALS
If electrons (negatively charged) are rubbed off of one material, the protons stay behind and the material becomes electrically charged. The material that gains the electrons also becomes electrically charged.
When a neutral atom loses electrons, it becomes positive (2- (-2) = 2+2)
When a neutral atom gains electrons, it becomes negative (2+(-2) = 2-2)
UNCHARGED MATERIALS
Before two materials are rubbed together, they are both neutral objects. If the positive and negative charges are the same, the object is neutral.
In a solid material, the nucleus stays in the center of the atom, but the electrons may be rubbed off a material. (the transfer of electrons)
REVIEW of positive and negative charge in the atom
Atoms contain subatomic particles: protons, neutrons, and electrons. A neutral object contains an equal number of both protons and electrons.
Friction & Electronic Transfer
Friction: when objects rub against each other. This results in an object losing electrons and the other gaining electrons. Electrons can stay on the surface of the new material or can travel through it.
Insulators & Conductors
Insulators: materials that DO NOT allow electrons to move easily. They can retain a static charge.
Examples: glass, plastics, ceramics, dry wood
Conductors: materials that DO allow electrons to move easily. They allow a charge to FLOW.
Examples: metals
CONDUCTIVITY
Conductivity is an indication of how easily charges can travel through a material. Electrons can move through almost all metals, which are conductors. Some electrons can move more easily in metals than others.
Rule: The higher the conductivity of a material, the more easily electrons can move through
Generating Static Charge & the Van de Graff generator
Van de Graff Generator: this uses friction to produce a huge amount of static charge on a metal dome. A moving belt produces a static charge at the base of the generator. The belt then carries the charge to the metal dome, where it is collected.
Examples: Jumping on a trampoline, slippers on a carpeted floor and then touching a metal doorknob, going down a plastic slide and touching someone.
Grounding-connecting: this connects all neutral points of conductors that carry currents to the Earth. This allows the electricity to flow in a low-resistance path.
ELECTRIC FORCE: push or pull between charged objects
Contact forces: forces that only affect objects that they touch.
Action-at-a-distance: forces that can affect an object without touching it.
Examples: An electric force is an example of an action-at-a-distance force.
The Laws of Static Charge
- Like charges repel
Positive-positive charges repel
Negative-negative charges repel - Opposite charges attract
Positive-negative attract - Neutral objects are attracted to charged objects
Positive-neutral attract
Negative-neutral attract
Coulomb’s Law
If the amount of charge increases, the electric force increases
If the distance between charged objects increases, the electric force decreases
Charging by Conduction
Objects become charged through contact
Examples: Friction, walking across a carpet and touching a metal doorknob.
When objects touch, electrons then move to their former object to their new one.
The Attraction of Neutral Objects
Induction explains why neutral objects are attracted to charged objects. Neutral objects are attracted to charged objects because the neutral objects are temporarily charged by induction.
Example: A balloon that is rubbed on a sweater (charged by conduction) and becomes negatively charged will stick to a neutral wall. The balloon’s negative charges will repel the wall’s negative charges. The wall becomes positively charged through induction.
Charging by Induction
When objects are charged without touching or making any direct contact. Electrons DO NOT move from one object to the other. Electrons reposition themselves in the object that becomes charged. The charge is temporary, since no electrons are transferred
Examples: Dust on TV screen -> a charged TV screen attracts the dust.
Electric Potential Energy & Voltage
Electrochemical cells: convert chemical energy into electrical energy
Battery: a single electrochemical cell or a combination of electrochemical cells that are connected.
Terminals: endpoints of an electrochemical cell or battery where connections are made.
Negative Terminal - end where electrons accumulate
Positive Terminal - end that has lost electrons
Producing Voltage
The two terminals in an electrochemical cell or battery are called ELECTRODES. These electrodes are in an electrolyte, which is a substance that conducts electricity.
Examples: Gatorade - electrical current is used in our bodies to be energized.
The two groups of cells
:Dry cells: electrolyte is a moist paste
Examples - used in flashlights and watches
Wet cells: electrolyte is a liquid
Examples - used in cars and motorcycles
The amount of voltage produced from an electrochemical cell depends on the types of metal (electrodes) and electrolyte used.
Most electrochemical cells produce 1.5V or 2V.
Electric Potential Energy
The electrical energy stored in an electrochemical cell
Energy is the ability to do work. Electric energy can do work.
*When unlike charges are moved farther apart, they gain electric potential energy.
Electric energy that is stored is potential energy.
Electric energy that is moving is kinetic energy.
Energy Around A Circuit
In a circuit:
1) Chemical energy in the battery separates positive and negative charges and gives electrons on the negative terminal electric potential energy.
2) Electrons move across the wire as they are repelled by the negative terminal and attracted to the positive terminal.
3) Potential energy is transformed into other forms of energy when it passes through a load
Examples: buzzers when transformed into sound energy.
Electric Potential Difference
Voltage: the amount of electric potential energy per coulomb of charge
Volt (V): measures voltage between two locations of charge separation
The actual electric potential energy is the product of both the voltage and the amount of charge
Energy = Voltage x Charge
Electric Current
Electric circuit: a complete pathway that allows electrons to flow
Circuit Components
Source: where the electrical energy comes from (electrochemical cell or battery)
Conductor: the wire through which electric current flows
Load: a device that converts into electrical energy into other forms of energy
When electrons pass through a load, they lose electrical energy once it’s converted to another type of energy. A load resists the flow of current.
Examples: light bulbs, heaters, radios
Switch: a device that can turn the circuit on or off by closing or opening the circuit. It controls the flow of current.
BRO, ELECTRONS ARE SO DAMN PUSHAYYY
All electrons have a negative charge, meaning that all electrons repel/push each other. Electrons in every part of a circuit are “pushing” each other, so when a circuit is closed, the load works immediately.
Circuit diagram
a diagram that uses symbols to represent different components of an electric circuit
