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Physics Unit 6
Question | Answer |
---|---|
The movement of electrons creates a ________ current. | electric |
________ fields are created by electric currents. | Magnetic |
An electric current runs through a metal spoon and induces ________. | a magnetic field |
A galvanometer's needle moves in response to a(n) ______. | electric current |
A voltmeter, a type of galvanometer, measures _______. | voltage |
You are lost in the woods; luckily, you have an instrument called a(n) ________ that helps you locate your position as its needle points to the magnetic north. | compass |
Loops in a current-carrying wire make a _______. | solenoid |
An electric current's strength is measured by a(n) ______. | ammeter |
To build a(n) _______, you wrap a conducting wire into a coil around a steel or iron core that becomes magnetized by the electric current. | electromagnet |
A solenoid is positioned between a stationary magnet's poles to produce a(n) ________, an instrument that can measure small electric currents. | galvanometer |
Who were the two scientists that simultaneously invented electric devices capable of converting electrical energy into mechanical energy? | Michael Faraday and Joseph Henry |
A ______ magnetic field deflects or repulses the magnetic field created in the wire loop, thereby making the loop rotate. | magnet's |
______ receive electric current from the stationary contacts. | Brushes |
______ receive electric current from DC power source. | Stationary contacts |
______ is produced by the loop's constant rotation, it turns the motor. | Torque |
A ______ receives electric current from the brushes, which then creates a magnetic field that is repulsed by the magnet's magnetic field. | Wire loop |
What is the induction of a magnetic field by an electric current? | electromagnetism |
What is the induction of an electric current in a conductor by magnets? | electromagnetic induction |
According to ________ ___, a coil's induced voltage is proportional to the product of the coil's number of loops and the rate at which the magnetic field changes. | Faraday's Law |
What is the formula used to find the input voltage of a transformer? | Ns=Vs Np Vp |
To reduce the input voltage from an electrical circuit to operate a machine at the correct input voltage, you need a(n) ______ transformer. | step-down |
A complete ______ is produced with one revolution of an armature. | cycle |
A regular AC current in the US operates at _____ Hz or cycles per second. | 60 |
What is the number of turns needed in secondary coil if voltage changes from 240 V to 120 V and the number of turns in the primary coil is 180? | 90 |
What do you use to turn up and down the volume of a voice amplifier? | rheostat |
You need to determine why a light has gone out in your car interior; you can check to see whether a ______ is burned out. | fuse |
What do you use to control a larger current by using a smaller current? | relay switch |
What do you use to ensure that if a circuit overload occurs in your house's electrical system, the house doesn't catch fire? | circuit breaker |
An advantage of AC current is how easy it is to convert ______. | voltages |
A disadvantage of _______ is that it is difficult to convert voltages. | DC current |
If we used DC current today for our residential electricity, we would have to install a __________ on each block. | power station |
Transmission lines carrying AC current have a low _________ so that they don't overheat. | amperage |
Transmission lines carrying DC current carried about 100 V and the electricity had to be delivered to the end point within a ______. | mile |
To generate electricity in the form of AC current, waterfalls, steam derived from burning fossil fuels, or __________ is used. | nuclear power |
The voltages of AC current are expressed in terms of _________. | DC voltage |
Every second, ______ fluctuates 60 times, meaning that for 60 "instants" no power is transmitted. | AC current |
Just before electricity enters a household, it passes through transmission lines going to a ________. | city substation |
An advantage of AC current is that the voltages in its transmission lines may be stepped up or stepped down by _________ to deliver the correct voltages at their end points. | transformers |
The battle of AC current vs. DC current ended in _________ being used as our electricity today. | AC current |
The electricity for AC current is generated in __________. | power stations |
At one point in history, this individual had a near monopoly on electrical power delivery systems. | Thomas Alva Edison |
A brilliant scientist from Croatia, ______ performed much of the research that resulted in the successful installation of AC systems. | Nikola Tesla |
The owner of General Electric, this man promoted the usage of DC current. | Thomas Alva Edison |
The individual who owned Westinghouse Electric Company and promoted the utilization of AC current was ________. | George Westinghouse |
Stay away from __________ lines, substations, and any installation designed to handle transmission-level power. | high-voltage |
If ________ is nearby, follow safety procedures. | lightning |
Never put anything ________ into an electrical appliance when it is plugged into a wall socket. | conductive |
Be careful with electrical appliances, especially around _______. | water |
Be careful around automobile _______. | batteries |
An AC motor that Nikola Tesla invented was the ________ motor. | polyphase induction |
Nikola Tesla's understanding that ___________ that were out of phase caused rotation is considered to be one of the ten greatest discoveries of all time. | alternating currents |
During the development of the first incandescent light bulb, a filament that was cheaper, ______, and more pleasant was sought after. | safer |
Tungsten, osmium, and carbon were all materials inventors used to compose ________ in early incandescent light bulbs. | filaments |
When a high temperature causes the emission of visible light by a body such as a light bulb, it is termed ________. | incandescence |
When a substance that has absorbed light or other electromagnetic radiation of a different wavelength emits light, it is called ________. | fluorescence |
The inventor who invented the first commercially produced and practical _________ light bulb was Thomas Alva Edison. | incandescent |
In 1912, Irving Langmuir introduced the idea of installing a coiled tungsten filament joined with __________ in an incandescent bulb's interior to produce a brighter light. | inert gas |
Scientist _________ applied a metal coating to the filament of an incandescent light bulb's interior to reduce smokiness. | Willis Whitnew |
A man who believed in Nikola Tesla's work, owned Westinghouse Electric Company, and championed the installation of AC current in the US was ____________. | George Westinghouse |
Electric energy provides two advantages over other energy forms, including being fairly plentiful and comparatively inexpensive to produce and ________. | transport |
A frosted interior for light bulbs was invented in 1925 by Marvin Pipkin and _________. | General Electric |
Two advantages of wind power are that it is __________ and does not _________. | inexhaustible; pollute |
Three disadvantages of wind power are that it needs ___________, is not __________, and it is _________. | room for tall towers; constant; noisy |
What source of power has advantages like being inexhaustible, nonpolluting, and used in locations where power grid is not available? | solar power |
What is a disadvantage of solar power? | expensive |
What source of power has an advantage of being inexhaustible but a disadvantage of requiring that water must have high potential energy due to gravity? | hydropower |
If a machine produces electric current or voltage from electromagnetic radiation, especially visible light from the sun, then it is _________. | photovoltaic |
An advantage of wind, solar, and hydropower is that they are ________. | inexhaustible |
Frequently, the use of solar-powered devices is in locations where electricity is ___________ from the energy grid. | not available |
In a photovoltaic cell, electrons in the upper panel move to a ___________ after being hit by sunlight and then flow towards another panel. | higher energy state |
A main concern in the hunt for new energy sources is that they do not _________ the earth. | pollute |
When electrons move, they produce a(n) __________ current. | electric |
An electric current may be measured by three instruments: a galvanometer, an __________, or a voltmeter. | ammeter |
A changing electric field in the form of an electric current creates a magnetic field is due to the phenomenon of _________. | induction |
To induce magnetism in a spoon, you run a(n) _____________ through it. | electric current |
A(n) __________ is a type of galvanometer that measures voltage. | voltmeter |
A compass' needle points to the __________. | magnetic north |
Making loops in a current-carrying wire creates a(n) __________. | solenoid |
An ammeter measures and electric current's strength in ________. | amperes |
Once a conducting wire is wrapped into a coil around a(n) __________, the wire's electric current magnetizes it, and you create an electromagnet. | iron core |
A galvanometer is produced by positioning a _________ between a stationary magnet's poles. | solenoid |
A magnet's south pole is attracted to the north pole of another _______ due to an attraction called magnetism. | magnet |
Scientists Joseph Henry and Michael Faraday invented electric devices that converted _____________ into mechanical energy. | electrical energy |
A _________ provides a DC power source for a DC motor. | battery |
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 ____________ in a DC motor's magnet deflects or repulses the wire loop's magnetic field created and as a result, makes the loop rotate. | magnetic field |
Electric current travels from the stationary contacts to the ________. | brushes |
The DC power source delivers electric current to the ___________. | stationary contacts |
The loop's constant rotation creates ______ that turns the DC motor. | torque |
The brushes send electric current to the _________, which then creates a magnetic field that the magnet's magnetic field repulses. | wire loop |
What protective device prevents circuit overloads from causing fires? | circuit breaker |
What protective device burns out in cars? | fuse |
What device enables you to change volumes in amplifiers? | rheostat |
What device enables you to deal with a smaller current instead of a larger current? | relay switch |
It is easy to convert the voltages in _________. | AC current |
The transmission lines that carry AC current have a low _______, so they overheat. | amperage |
It is difficult to convert the voltages in ________. | direct current |
In our country's history, there was a battle between whether we would use AC or DC current; ____ current's advantages were responsible for its use today. | AC |
AC current voltages may be stepped up or stepped down by _______. | transformers |
_________ held a monopoly on electrical power delivery systems for a while, promoted DC systems, invented the first practical incandescent light bulb, and owned General Electric. | Thomas Alva Edison |
Who is the man who owned Westinghouse Electric Company and championed the use of AC current? | George Westinghouse |
Who is the Croatian scientist who did much research on AC systems and motors? | Nikola Tesla |
Scientists around the world are seeking __________ energy sources. | renewable |
The production of electric energy has depleted large amounts of resources, plus it produces ________. | pollution |
In early incandescent light bulbs, 98% of the energy was converted into ________, not light. | heat |
_________ is generated due to the kinetic energy of falling water. | hydroelectricity |
Power derived from hot rocks is _________ energy production. | geothermal |