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Direct Current (DC)
Definition: current in which charged particles (electrons) flow through a circuit in only one direction
Extra Info: DC is found in batteries.
Example: Cell phone, flashlight. (use batteries)
Alternating Current (AC)
Definition: current in which charged particles (electrons) move back and forth in a circuit
Extra Info: AC does not have a net direction of flow (it is zero) because the amount of electrons that go one way is equal to the amount moving in the opposite direction, so they cancel each other out and leave zero.
- Example: Refrigerator, dryer. (Plug into wall)
Definition: an electrical device that changes the size of the potential difference of an alternating current
Extra Info: There are different types of transformers. Transformers that increase potential difference are called step-up transformers, while ones that decrease it are called step-down transformers.
Definition: a safety device that is in series with other circuits, which lead to appliances and outlets
Extra Info: Circuit breakers work by being heated by the current, and if the current is too high, a part of the circuit breaker will snap from the heat, causing an open circuit.
Definition: a safety device mostly found in old buildings, and does a job similar to the circuit breaker using a similar method
Definition: the rate at which an appliance uses electrical energy
Extra Info: The power rating of an appliance can be found on an EnerGuide label. It is used to find the energy used, and the cost of the energy.
Example: The power rating of a typical toaster is 1.1kW.
Definition: a unit of electrical power
Extra Info: 1,000 watts is equal to one kilowatt.
Definition: a practical unit of electrical power
Extra Info: Kilowatt is often used over watt because most devices use large amounts of electricity, easier measured in kilowatts. 1,000 watts is equal to one kilowatt.
Definition: the energy that is used by an appliance at a given setting; determined by multiplying the power rating of an appliance (P) by the length of time it is used (t)
Definition: the practical unit of electrical energy
Extra Info: Since most appliances are used for hours at a time, kW.s (kilowatt x seconds) is not as practical.
Definition: a label that gives details about how much energy an appliance uses in one year of average use
Extra Info: On EnerGuide labels, there is often a scale that shows how much energy the appliance uses compared to other appliances of the same type (the appliance that uses the least amount of energy would be better money wise).
Definition: a meter that records the total electrical energy used hour by hour and sends the information to the utility company automatically
Extra Info: Ontario's goal was to replace all old meters with smart meters in every house by the year 2010.
Time of Use Pricing
Definition: a system of pricing in which the cost of each kW.h of energy used is different at different times of the day
Example: The cost for energy would be higher in the morning when most people heat their houses.
Definition: the electricity that is consumed by appliances or devices when they are turned off
Extra Info: This can be prevented by unplugging the appliance/device and turning off any power rods.
Definition: the ratio of useful energy output to total energy input, expressed as a percentage
Extra Info: Percent efficiency can be found by dividing the useful energy output by the total energy input, then multiplying by 100.
- Example: (1kW= 1kJ)
- Percent efficiency=
- useful energy outputtotal energy input x100
- 168 kJ198kJ x100
- Therefore, the percent efficiency is approximately 85%.
Definition: the continuous minimum demand for electrical power
Extra Info: The electrical energy generating method optimally suited for meeting the base load is nuclear energy, and hydroelectric energy.
Hydroelectric Power Generation
Definition: the generation of electrical power using a source of moving water
- Example: Dam station, run-of-river station (both are used to turn turbines).
- Dam station:
- Run-of-river station (diagram):
Definition: a demand for electricity that is greater than the base load and is met by burning coal and natural gas
Definition: the greatest demand for electricity, which is met by using hydroelectric power and natural gas
Renewable Energy Source
Definition: a source of energy that can be replaced in a relatively short period of time
Example: Hydroelectric energy, biomass energy (biofuels), wind energy, solar energy.
Non-renewable Energy Source
Definition: a source of energy that cannot be replaced as quickly as it is used
Example: Fossil fuel energy, nuclear energy, coal energy.
Definition: energy that is directly converted from the Sun into electricity
- Extra Info: This is done using solar panels, and the photovoltaic effect.
- Solar panels are very expensive, but cost little to operate, but the cost of solar panels will decrease majorly in the coming decades.
Definition: the generation of a direct current when certain materials are exposed to light (e.g. the material of solar panels)
Definition: energy that is generated from plant and animal matter
Extra Info: This source of energy is renewable, and only releases as much carbon dioxide into the atmosphere as the plants absorbed during their growth ("carbon neutral"). A large supply of biomass is not always available for this however.