INT 222 Exam 2 - Electricity

What is electricity?

a form of energy that occurs naturally in unusable forms such as lightning, static discharge, or galvanic action.

all atoms contain positively and negatively charged particles; the magnetic effects of these particles are what we call electricity

What are conductors?

materials that allow the flow of electric charge freely (ex: gold, silver, platinum, aluminum, copper, water)

What are insulators?

materials that restrict the movement of electric charge (ex: plastic, glass, rubber, porcelain)

Electric Current (Ampere - A)

flow of electricity through a conductor

Electric Potential (Volt - V)

the force that moves electrons, aka voltage

Electric Resistance (Ohm - Ω)

opposition to the flow of current

Ohm’s Law

I = V/R

Current (I) is directly proportional to voltage (V) and inversely proportional to Resistance (R)

Electric Current Conversion to Heat

light bulb filaments or heating elements have resistance, leading to voltage drop and energy conversion into heat and light

Electric Current Conversion to Heat Formula

W = AV

(Watts = Amps x Volts)

Series Circuits

components are connected along a single path

same current flows through all components

Parallel Circuits

components are connected so that the same voltage is applied to each component

Direct Current (DC)

voltage flows in one direction (ex: batteries, solar cells)

Alternating Current (AC)

voltage oscillates between positive and negative polarities

Steam Turbine Methods

Coal-fired plants

gas-fired plants

oil-fired plants

nuclear plants

Water Turbines

hydro-electric dams

tidal flow plants

Wind Turbines

wind-generated electrivcity

Photovoltaic Panels

converts sunlight directly into electricity (ex: solar panels)

Total Energy System

uses internal combustion engines fueled by natural gas to generate electricity

The amount of volts used in Residential

AC 120/240 volts (single-phase)

the amount of volts used in large commercial or industrial

AC 277/480 volts (three-phase)

Power Grid

energy losses occur when electricity is transmitted over long distances

losses are minimized by increasing voltage and reducing amperage using transformers

reduced current (amps) allows for smaller wires to be used

Transformers

devices that change voltage levels in a power system

Power to a building

three wires connect the transformer to the building, a neutral wire and two hot wires

Neutral Wire

no electric potential between wire and ground

Hot Wires

energized wires with a potential difference of 115 volts each

Power distribution within a building

to distribute energy within a building u need a service panel, neutral wire, black “hot” wire, and red “hot” wire

Service Panel

central hub for electricity distribution

Single Breaker

used for 115V or 120V circuits, connected to either the black or red bar

Double Breaker

used for 230V or 240V circuits, connected to both black and red bars

Circuit Breaker

acts as a switch for circuits

automatically shuts off when excess current flows to prevent damage or fire hazards

The speed at which a fuse blows depends on what?

the current flowing through it

the material of the fuse strip

Fuses

interrupt excessive current to prevent overheating and fire

composed of a metal strip that melts when too much current flows

Types of electric conduit

rigid metal conduit

BX cable (flexible metal conduit)

Romex cable (flexible plastic conduit)

Electrical Conduit

protects and routes electrical wiring

Outlet-Box

metal or plastic box that secures electrical receptacles, lighting fixtures, and switches

Electrical outlet codes

minimum number of receptacles per room

maximum number of receptacles per circuit

maximum horizontal distance between receptacles in a room

Currents Fence for Open Workspaces

technology management system for flexible planning

can be integrated with adjustable height desks

c-leg desks may be end-supporting along the fence

GFCI Outlet

an outlet required in wet areas like kitchens, bathrooms and outdoor spaces

it protects against electric shock by shutting off power when it detects and imbalance in current flow