Download Electricity and Solar Energy Quiz Study Guide

Electricity and Solar Energy Quiz Study Guide.
1. Electricity—electrical current used as a power source.
2. Electric Current—the amount of electrical charge passing through a given area in a
given time. Measured in Amps. The current is the “amount” of electricity present. 1/10
of an amp of current can stop a human heart. There are two types of electrical current:
a. Direct Current (DC)—current flows in ONLY ONE direction (negative to
positive). DC current is easily controlled and used in most small electronic devices.
b. Alternating Current (AC)—the current flows back and forth in TWO
directions in a wave format. The height of the wave (amplitude) is equal to the voltage.
AC is not as easy to manipulate or control as DC, but is easier to transmit over long
distances, so it is used in power plants and distribution systems.
3. Voltage—the amount of “push” behind the electrical current. Also known as EMF or
electromotive force or electrical potential. Voltage is measured in volts. Higher
voltages may “jump” from one place to another (i.e. lightning) through the air.
4. Generation of electricity—requires three components:
a. magnets
b. wire in a loop
c. motion—must be motion for magnets/wire to make current flow
5. Electrical power generation—Typical construction uses a turbine that spins due to
steam or hot air, this then turns a generator, which contains magnets and wires and
makes electricity. Electrical power is measured in watts. One watt is one Joule per
second.
6. Electrical energy transfer—Electrical power stations use generators driven by either
non-renewable or renewable resources. The power generated is transmitted through
high voltage wires and is AC (alternating current). Voltage and current may be
transferred back and forth using an electrical transformer, a set of coils and magnets in
a particular ratio. Electrical power is measured in kilowatt hours on a power meter on
or near its point of consumption (i.e. house or building). A breaker box distributes
power from the power company to a building for consumption.
7. Non-renewable resources include: fossil fuels—burning of coal, oil, natural gas;
and nuclear energy—using uranium in nuclear reaction to heat water. These resources
cannot be naturally replenished.
8. Renewable resources include: solar, wind, hydroelectric, geothermal, and ocean
wave generation, etc. These resources are naturally replenished.
9. Efficiency—a measure of how well a resource or device can do its intended function
or job. Electrical efficiency is often given as a percentage. No device is 100% efficient
due to some loss by thermal energy or heat.
10. Efficiency of Resources: Some typical efficiencies of energy resources include:
a. Hydroelectric—85%
b. Wind—50%
c. Nuclear—34%
d. Fossil fuels—30%
Some efficiencies will vary depending on the age, type and design of power plants.
11. Electrical consumption—the use of electrical energy by appliances and consumer
devices. The electrical devices that use the most electrical energy are: Heating, Air
Conditioning, Water heating, Pools and pool systems, refrigerators, freezers, and
lighting.
12. Conductors—materials that easily allow electrical current to flow through them.
Copper, aluminum and some other metals are good conductors.
13. Insulators—materials that prevent the flow of electrical current. Rubber, plastics,
wood, and air are some of the best insulators. Wires are often coated in plastic or
rubber materials to insulate them so that the electrical current will not jump off at higher
voltage or cause damage or injury to anything nearby.
14. Resistance—is a measure of a material’s ability to oppose the flow of electrical
current. Resistance is measured in Ohms. Materials with higher resistance tend to
dissipate electrical energy in the form of heat (they get hot faster).
15. Circuit—electrical current has to flow in a circular loop so that the electrons have a
complete path of travel. A closed circuit is a complete loop allowing electrical current to
flow. An open circuit contains a break where electrons cannot flow.
16. Circuit types: There are two basic types of electrical circuits:
a. Series—a series circuit has ONLY ONE path for electrical current to flow
through it. In a series circuit the voltage is shared between all of the devices in the
circuit and the current is the same in all parts of the circuit.
b. Parallel—a parallel circuit has MORE THAN ONE path for electrical current to
flow through it. In a parallel circuit the voltage is the same between all of the devices
and the current is shared between all of the devices in the circuit.
17. Lighting: Electrical lighting is one of the major uses of electricity. There are three
basic types of lighting used:
a. Incandescent—the typical light bulb type, invented by Thomas Edison,
passes electricity through a metallic filament, which heats up and glows, producing
light. This process is subject to failure due to the filament burning through, so bulbs are
typically air tight or contain a small amount of gas to slow this process. Tungsten is a
typical filament material due to its resistance to heat breakage. Halogen gas is
sometimes added to increase brightness and lengthen filament life. Incandescent bulbs
are typically 10% efficient and not very economical, but they can produce a lot of light
when needed. (spotlights)
b. Fluorescent—a tube of mercury gas is electrified by higher voltages and then
glows. The energy from the glowing gas is used to illuminate a phosphor coating on the
tube that produces light. Fluorescent tubes use less energy, but the color of the light is
usually harsh and limited. They are economical, but not very high quality. Their
brightness is limited, but they can stay on a long time with little energy use.
c. LED—Light emitting diode—a set of silicon pieces contain a P/N junction that
allows electrons to flow through it and produces photons (light) usually of only one color.
Combinations of LEDs can be used to produce multiple colors. New LED technologies
have produced brighter LED’s but usually their brightness is limited. Even though they
are expensive to make and buy, they will last significantly longer than other types of
bulbs—30 years or more, so they are very economical.
18. Lighting measurements: Light output is measured in lumens. The efficacy of a
light bulb is given as the lumens per watt that it produces. This is a comparison of the
ability of the bulb to produce usable light.
19. Solar energy—The sun is the most abundant source of energy on Earth. The
amount of solar energy that strikes the surface of the Earth depends on location based
on the TILT of the Earth. In the Northern Hemisphere, areas farther south will receive
more solar energy during the summer months.
20. Solar energy collection—solar energy can be collected and used by two methods:
a. Photovoltaic cells (PV)—solar cells use a set of semiconductor wafers
separated by a P/N junction where light is used to excite photons, which can then carry
electrons with them to collectors (small wires) and then be channeled to flow into a
circuit. They essentially use the light energy and convert it into flowing electrons or
electricity.
b. Solar Thermal—solar thermal collectors use dark colored high-conducting
(copper) materials to absorb and transmit the heat energy from the sun and use it to
warm up a fluid. There are two types:
*Passive solar thermal—uses the difference in temperature to make the
liquid flow through the collector
*Active solar thermal—uses a pump system to push the liquid through
the collector.
Some solar collecting systems use solar concentrators—reflectors designed to focus
the light energy of the sun onto the solar thermal or PV systems. Solar energy cooking
can be very beneficial in third world countries to help reduce food-borne illness and
provide better health to the population.
21. Energy safety—Electrical energy can be dangerous, some safety precautions that
should be taken include:
a. Grounding—be sure that high voltage devices have appropriate grounding so
that any stray electrical charges will be transmitted to the ground.
b. Insulation—use proper insulating materials to ensure that electrical current
does not jump or short out.
c. Education—know to stay away from high voltage transformers and AC wiring.
Never plug in any appliances or devices that may have shortages or are unsafe.
d. Water—water can conduct electricity, so keep electrical devices away from
water unless designed for use in or around water.
Remember that there are electrical codes that describe the proper use of electricity.
Always be careful around electricity and leave the complex electrical jobs to the
qualified electricians.