Electricity Glossary Terms Chapter 12

-current in which charged particles travel through a circuit in only one direction

NOTE: this occurs in the current from a cell as it travels from the negative terminal to the positive terminal

-current in which electrons move back and forth in a circuit

NOTE: there is zero net movement of electrons in either direction

NOTE: this allows us to transmit more energy without much loss of the energy as heat

• EXAMPLE: generating a current in a coil by moving magnet in and out of the coil is AC as the current moves in one direction when the pole of the magnet is inserted into the coil and in the opposite direction when taken away
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-an electrical device that changes the size of the potential difference of an alternating current

NOTE: does not work in direct current

NOTE: transformers that increase the potential difference are called step-up transformers and, transformers that decrease the potential difference are called step-down transformers

EXAMPLE: when a cell phone is plugged into a wall socket, a transformer reduces the potential difference from 110V to the potential difference needed

-safety device that is place in series with other circuits, which lead to appliances and outlets

NOTE: located in distribution panels

NOTE: limits the amount of current to a set value and prevents overheating in wires and fires

• EXAMPLE: connected in series with meter and in parallel with other breakers so when the current is too large, circuit breakers heat then bend and break contact with another part opening the circuit (when that occurs circuit breaker must be reset)
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-a safety device that is found in older buildings and some appliances; like a circuit breaker, it is placed in series with other circuits, which lead to appliances and outlets

NOTE: located in distribution panels

• EXAMPLE: they contain a metal conductor that melts at a certain temperature that goes with a set amount of current, which creates an open circuit and stops the current (when that occurs it must be replaced)
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- the rate at which an appliance uses electrical energy

NOTE: measured in watts (W) or kilowatts (kW)

-a unit of electrical power

NOTE: 1W=1J/s

-a practical unit of electrical power; 1kW=1000W

-the energy that is used by an appliance at a given setting; determined by multiplying the power rating of an appliance by the length of time it is used

NOTE: determined by multiplying the power rating by the length of time used (E=Pxt) and measured in kW∙H (kilowatt-hours)

-the practical unit of electrical energy

-a label that gives details about how much energy an appliance uses in one year of normal use

-a meter that record the total electrical energy used hour by hour and sends this information to the utility company automatically

-a system of pricing in which the cost of each kW∙H of energy used is different at different times of the day

NOTE: used as off-peak, mid-peak and, on-peak

-the electricity that is consumed by an appliance or device when it is turned off

EXAMPLE: TV's, clocks and external power require phantom load

TIP: just unplug your device or appliance to save on energy and prevent a phantom load

-the ratio of useful energy output to total energy input, expressed as a percentage

NOTE: percent efficiency=useful energy output/total energy input (Pxtx100)

-the continuous minimum demand for electrical power

NOTE: in Ontario this is generated in the early morning hours when most people are asleep

-the generation of electrical power using a source of moving water

NOTE: the two types of hydroelectric power generation are dam stations and run-off river stations

ADVANTAGES: environmentally friendly, produces almost no greenhouse gases, is about 90% efficient and it is a renewable energy source

DISADVANTAGE: large areas of land must be flooded (which may lead to the decay of vegetation and production of methaneFalls)

LOCATION: Niagara

-a demand for electricity that is greater than the base load and is met by burning coal and natural gas

-the greatest demand for electricity, which is met by using hydroelectric power and natural gas

NOTE: cost of providing electricity increases

NOTE: higher on-peak rates apply

-a source of energy that can be replaced in a relatively short period of time

EXAMPLE: hydroelectric energy

-a source of energy that cannot be replaced as quickly as it is used

EXAMPLE: fossil fuels

-energy that is directly converted from the Sun into electricity

ADVANTAGES: free fuel, little negative impact on the environment

DISADVANTAGES: not very efficient or concentrated and the systems are very expensive

-the generation of a direct current when certain materials are exposed to light

EXAMPLE: calculators have solar cells

NOTE: it is a challenging task to collect and convert the huge amounts of energy from the sun to electrical energy in a energy efficient and cost efficient way

-energy that is generated from plant and animal matter

NOTE: is carbon neutral however it adds carbon dioxide to the atmosphere

ADVANTAGES: results in less acid rain (compared to the burning of fossil fuels), and there are no heavy metals emitted

DISADVANTAGES: there are not large supplies of biomass