Physics Unit 6
Identify the type of electrical current the following descriptions are connected with. Thomas Alva Edison
DC
Identify the type of electrical current the following descriptions are connected with.Voltage is difficult to convert from one to another.
DC
required a nearby power station
DC
with a supply voltage of 100 volts and limited range of transport of electricity of less than one mile
DC
alternating current motors and transformers
Nikolas Tesla
State Faraday's law.
The induced voltage in a coil is proportional to the product of the number of loops within the coil and the rate at which the magnetic field changes within those loops.
Problems with arc lamps included:
They were expensive to produce and operate; They burned out quickly; They sometimes burned down the building where they were being used
His company built the electric lines in Buffalo, New York. checkCorrect
Thomas Alva Edison
owner of General Electric
Thomas Alva Edison
He claimed AC electrical power was extremely dangerous in a disinformation campaign.
Thomas Edison
first practical and commercially feasible light bulb (1879)
Thomas Edison
AC voltages stated in terms of the equivalent DC voltage would provide the same power.
true
Faraday's law of induction shows the induced voltage is proportional to the number of turns in the coil.
true
If two secondary coils having the same number of loops are wound on the same iron bar with a primary coil, both secondary coils will have the same induced voltage.
true
Filaments of modern incandescent bulbs: ________
tungsten
GFCI outlets shut off the power if there is a(n) ___________ of current between the two supply wires.
unbalance
A galvanometer that measures voltage is a(n) ________.
volmeter
A magnet inserted quickly in an out of a coil creates a(n) ___________ across the coil of wire.
voltage
Number the following actions that occur when heat from sunlight is used to produce steam, which is then used to create electricity. (1-5 with 1 being the first step)
1. produce heat (to) 2. produce steam (which will) 3. power a turbine (which will) 4. drive a generator (which will) 5. produce electricity
Today wind power provides ___ of commercially created electricity in t
10%
A musician flies from England to Canada where the voltage is 120 VAC. Her amplifier operates on 240 VAC. In order to use her amp, she uses a step-down transformer that has _____ turns on the primary coil and 600 turns on the secondary coil.
300
AC electricity in the United States alternates at ________ times per second.
60
number of turns in secondary coil/number of turns in primary coil
= output voltage/input voltage
fluorescent light bulb (1939)
General Electric
tungsten halogen lamp
General Electric
_____ was the owner of the company that won the AC/DC war.
George Westinghouse
What are some rules should be followed to prevent electrical accidents?
If lightning is in the area, go indoors or get inside a car.; Avoid burns by being careful when working on 12 volt automobile systems.; Be careful when using electrical appliances in damp conditions.; Be careful when using jumper cables, put positive to positive.; Stay away from high-voltage lines
coiled tungsten filament joined with inert gas inside bulb—brighter light
Irving Langmuir
A current is moving though a wire and the wire is placed inside a magnetic field. What will happen to the wire?
It will be deflected in a perpendicularly to the magnetic field.
The inventor of the relay was _____.
Joseph Henry
Who invented electric devices that worked on the principle that electrical energy could be converted to mechanical energy?
Joseph Henry & Michael Faraday
His designs and patented AC electrical components were awarded the contract for the power grid in Buffalo, New York.
Nikolas Tesla
At one point, he had a monopoly on electrical power delivery system.
Thomas Alva Edison
How do photovoltaic cells work?
When light strikes the upper panel, electrons are moved into a higher energy state and flow from the material toward another panel.; The panel where electrons have moved has a positive charge. These charges are collected in a material between the negative and positive panels
an instrument that measures electric current
ammeter
Every half revolution of the wire loop in a DC motor ________ reverses the current, thereby changing the direction of the magnetic field of a DC motor's wire loop.
armature
The ________, which is free to turn, holds a _______
armature; loop of wire
An important feature of Nikola Tesla's induction motor was that ran on AC current and had no ______.
brushes
The armature has _______, which make contact with a set of __________
brushes; commutator
Moving _________ create an electric current.
charges
protection from circuit overload
circuit breaker
The abbreviation CFL stands for _____.
compact fluorescent lamp
Define photovoltaic:
concerned with, or producing electric current or voltage caused by electromagnetic radiation, especially visible light from the sun
A problem with both wind power and solar power is that they are not ____________.
constant
You need to dim a room's lights by varying the amount of current.
dimmer
In 1831, Michael Faraday of England and Joseph Henry (December 17, 1797-May 13, 1878) of the United States invented electric devices that converted ___________ to mechanical motion.
electricity
Some advantages of electric energy over other types are:
electricity is fairly plentiful; relatively inexpensive to produce and transport.
A coroner announces that a person died due to ______ when he was struck by lightning while pruning a tree.
electrocution
A relay uses a(n)____________ to close a switch to control a large current with a small current.
electromagnet
The creation of an electrical current through the use of magnets is called __________ induction.
electromagnetic
The reason an electric current can create a magnetic field is due to the phenomenon of ___________.
electromagnetism
If a magnet is being inserted into a coil, _________ will move in the wire if it has a complete circuit.
electrons
Since DC is smoother than AC, transformers work better on DC.
false
The emission by a substance that has absorbed light or other electromagnetic radiation of a different wavelength is called ______.
fluorescence
Two non-renewable resources we are currently using for electricity are:
fossil fuels, including coal, oil, and natural gas; radioactive materials
An electrical wire in a car's circuit becomes overloaded.
fuse
an instrument made of a wire loop between a permanent, stationary magnet's poles that detects the presence and strength of small electric currents
galvanometer
A useful electric ____ is created when a wire loop is continuously rotated within as stationary magnetic field.
generator
Hot rock and hot water close to the earth's surface can be tapped to generate electricity through the process of _____.
geothermal electricity production
The principle behind the operation of an arc light is _____.
high voltage that creates an arc between carbon electrodes
falling water
hydro-power
tidal motion
hydro-power
The emission of visible light caused by a high temperature is called _____.
incandescence
Thomas Alva Edison patented a(n) ________ bulb that contained a carbon filament with the majority of oxygen removed.
incandescent
If the current in a cell is increased, the strength of a magnetic field is ___________.
increased
Faraday's Law states that if you rapidly insert a magnet in and out of a coil, the coil's ________ will be proportional to the product of the number of loops in the coil and the rate at which the magnetic field changes.
induced voltage
The invention of the AC ___________ overcame the major objection of using AC instead of DC.
induction motor
How should a electromagnetic induction be defined?
induction of an electric current in a conductor by magnets
A great advantage afforded by wind power, solar power and hydro-power is that they are all _____.
inexhaustible resources
The body of the motor is a large, curved ______. The N and S poles are separated by a gap.
magnet
Every electric current produces a __________ field.
magnetic
the property of magnets that is attraction
magnetism
produced compact fluorescent lamps (CFLs) (1970-2000)
many manufacturers
If a compass is brought near a wire carrying an electric current, the compass' _______ will move.
needle
The ________ on a galvanometer moves when it detects an electric current.
needle
You plug in your printer, your computer, your monitor, your speakers, and your space heater. Suddenly, all of these devices stop working. You the circuit has just suffered a(n) _____.
overload
The contacts are connected to a DC ______ ______, such as a batter
power source
A large current needs to be turned on using a small current.
relay switch
The world is in need of _________ resources that will not _______ the earth.
renewable; pollute
In order to locate a wind-generating equipment, these may be considered disadvantages:
room for tall towers; steady wind of 6.9 m/s or more; vacant land where the noise of wind generators will not disturb resident
Why were glowing filaments with low voltages sought after for lighting rather than arc light?
safer; cheaper; more pleasant
The two most common causes of electrical accidents are:
short circuits; circuit overloads
Sun's enormous amount of energy
solar power
photovoltaic cells
solar power
Some solutions to the non-renewable resource problem are:
solar power wind power hydropower nuclear fusion
A(n) _________________ is made of many turns of wire in a cylindrical shape.
solenoid
Loops in a current carrying wire that creates a magnetic field within the wire.
solenoid
Making loops in a current-carrying wire creates a(n) _____.
solenoid
Instead of moving a magnet in and out of a coil, it is often easier to have a __________ magnet and a ________ wire inside a magnetic field.
stationary; rotating
An electric generator or motor has a stationary field magnet; this part is called the _______.
stator
A musician travels to Belgium where the voltage from a wall outlet is 230 V. She needs to plug in an electric amplifier that operates on 115 V. So she does not blow up her amp on stage, she uses a ____-____ transformer that has a primary coils with 500 turns and a secondary with ___ turns.
step-down; 250
Define electromagnetism.
the creation of a magnetic field by an electric current
Define hydroelectricity:
the kinetic energy of falling water drives a turbine which operates a generator to produce electricity
Two difficulties encountered with the use of the arc lights were ________ and _________.
the light was harsh; the light was too bright
According to Faraday's law, which coil would register the greatest voltage if the the same magnet were moved in and out of the coils at the same rate?
the one on the right
kinetic energy of air movement drives a turbine
wind power
systems used in locations where electrical devices cannot be connected to the energy grid
wind power; solar power
Voltage is easy to convert from one to another because transformers can be used.
AC
ability to transmit power at a higher voltage and lower current, thereby reducing losses due to resistance
AC
house wiring in most homes at 120 V or 240 V
AC
A transformer outputs 200 watts into a motor. The input is 120 volts. Assuming no losses, how much current flows through the primary coil?
1.67 amperes
A primary coil has 360 turns, while secondary has 120 turns in a transformer. The output voltage is 220 V. What is the input voltage, and what type of transformer is it?
600 v; step-down
The original incandescent light bulbs converted __% of the electrical energy they consumed into ____ instead of light.
98; heat
Can be generated at large power stations and stepped up through the use of transformers to 500,000 volts or more.
AC
Form of electric power used in most of today's homes and industrial locations is _____.
AC
Identify the type of electrical current the following descriptions are connected with. George Westinghouse
AC
Identify the type of electrical current the following descriptions are connected with. Nikola Tesla
AC
Power sources for generating plants include falling water, steam captured by burning fossil fuels or by nuclear power.
AC
an instrument that helps determine directions due to a freely rotating magnetic needle that points to the magnetic north
compass
With the current flowing in the direction of the arrow, in which direction will the magnetic field flow?
counter-clockwise
The insertion of a(n) ___________ core creates a magnetic field much stronger than that of the original coil.
iron
A secondary transformer has 80 turns, while the primary has 240 turns. The input voltage is 120 V. What type of transformer and what is the output voltage? check
step-down; 40 v
The discovery by Nikola Tesla that is considered to be one of the 10 greatest discoveries of all time was _____.
that out-of-phase alternating currents caused rotation
The function of the stator in Tesla's induction motor was _____.
to rapidly change the magnetic polarity in the stator causing the armature (rotor) to follow
