Electricity Glossary Terms - Chapter 12

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 Author: ReneeF ID: 287026 Filename: Electricity Glossary Terms - Chapter 12 Updated: 2014-11-02 16:08:45 Tags: Electricty Folders: Description: Grade 9 Science Electricity Terms - Chapter 3 of 3 Show Answers:

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1. Direct Current (DC)
• def:current in which charged particles travel through a circuit in only one direction (negative terminal to positive terminal)
• e.g: the current from a cell

2. Alternating Current (AC)
• def: current in which electrons move back and forth in a circuit
• no net movement of electrons in either direction
• e.g: generating a current in a coil by moving a magnet into and out of a coil of wire. the current moves in one direction when a pole of the magnet is inserted into the coil and in the opposite direction when the magnet is removed
• allows us to transmit a lot of energy without much loss of energy as heat

3. Transformer
• def: an electrical device that changes the size of the potential difference of an alternating current
• do not work in direct current
• e.g: when a cell phone is plugged into a wall socket, a transformer reduces the potential difference from 110V to the potential difference needed.
• transformers that increase the potential difference are called step-up transformers and transformers that decrease the potential difference are called step-down transformers

4. Circuit Breaker
• def: a safety device that is placed in series with other circuits, which lead to appliances and outlets
• located inside a distribution panel
• Safety Purpose: limits amount of current to a set value and prevents overheating in wires and possible resulting fires
• e.g: connected in series with meter and in parallel with other breakers. when current is too large, circuit breaker is heated and then bends and breaks contact with another part, opening the circuit. the circuit breaker must be reset.

5. Fuse
• def: 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
• located in a distribution panel
• safety purposes are the same a circuit breakers
• e.g: contains a metal conductor that melts at a temperature that goes with a set amount of current, which creates an open circuit and stops the current. it must then be replaced.

6. Electrical Power
• def: the rate at which an appliance uses electrical energy
• measured in watts (W) or kilowatts (kW)
• 1kW=1000W
7. Watt (W)
• def: a unit of electrical power; 1000 W=1 kilowatt
• 1W=1J/sec
8. Kilowatt (kW)
def: a practical unit of electric power; 1 kW=1000 watts
9. Electrical Energy (energy input)
• def: the energy that is used by an appliance at a given setting (high, medium, low)
• is determined by multiplying its power rating by the length of time it is used
• E=PxÎ”t
• measured in kilowatt-hours (kW.h)

10. Kilowatt-hour (kW.h)
def: the practical unit of electrical energy
11. EnerGuide Label
def: a label that gives details about how much energy an appliance uses in one year of normal use

12. Smart Meter
def: a meter that records the total electrical energy used hour by hour and sends this information to the utility company automatically

13. Time of Use Pricing
• def: a system of pricing in which the cost of each kW-h of energy used is different at different times of the day
• broken down into off-peak, mid-peak, and on-peak times for pricing

• def: the electricity that is consumed by an appliance or device when it is turned off
• TV's, clock displays and external power require phantom load
• easiest way to prevent a phantom load is to unplug an appliance

15. Efficiency
• def: the ratio of useful energy output to total energy input, expressed as a percentage
• percent efficiency=useful energy output/total energy input (PxÎ”t)x100

• def: the continuous minimum demand for electrical power
• the minimum amount of electrical power in Ontario is generated in the early hours of the morning when most people are asleep, and is about 12 000MW

17. Hydroelectric Power Generation
• def: the generation of electrical power using a source of moving water
• there are 2 types of hydroelectric plants: dam stations and run-of-river stations
• Advantages: economically and environmentally friendly, produces almost no smog or greenhouse gas, renewable energy source, low operating costs, about 90% efficient
• Disadvantages: large areas of land must be flooded when reservoirs are built, which leads to the decay of vegetation and production of methane that can kill fish
• Location: Sir Adam Beck Generating Stations near Niagara Falls

• Â Â
• Dam Station Â  Â  Â  Â  Â  Â  Â  Â  Â Run-of-River Station
def: a demand for electricity that is greater than the base load and is met by burning coal and natural gas (between 15 000 and 20 000MW)

• def: the greatest demand for electricity, which is met by using hydroelectric power and natural gas (above 20 000MW)
• cost of providing electricity increases (especially if the electricity must be purchased from outside Ontario)
• higher on-peak rates apply

20. Renewable Energy Source
• def: a source of energy that can be replaced in a relatively short period of time
• e.g: hydroelectric energy

21. Non-renewable Energy Source
• def: a source of energy that cannot be replaced as quickly as it is used
• e.g: fossil fuels

22. Solar Energy
• def: energy that is directly converted from the Sun into electricity
• Advantages: the fuel is free and there is very little negative impact on the environment
• Disadvantages: solar cells are not very efficient (at best 25% efficient), it is not very concentrated, and solar energy systems are very expensive

23. Photovoltaic Effect
• def: the generation of a direct current when certain materials are exposed to light
• e.g: wrist watches and calculators that have solar cells
• the challenge is to collect and convert the huge amounts of energy from the Sun to electrical energy efficiently and cost-effectively

24. Biomass Energy
• def: energy that is generated from plant and animal matter
• adds carbon dioxide to the atmosphere, but is carbon neutral
• Advantages: compared to burning fossil fuels, the use of biomass energy results in much less acid rain and there are no heavy metals emitted
• Disadvantages: there are not large supplies of biomass, unless crops and forests are used for this purpose

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