Q&A Hero

Q: Global warminga. has not yet been observedb. has been caused by increasing levels of carbon dioxide in the atmospherec. has led to a depletion of the ozone layer in the atmosphered. has no serious consequences

Q: What's the Big Bang? a. the creation of the universe b. microwave radiation from all directions in the sky c. the Hubble relation d. a punk rock band

Q: AM radio stations have greater range than FM stations becausea. AM is more efficient than FMb. they have more powerful transmittersc. their lower frequency radio waves reflect off the ionosphered. none of the above

Q: The wavelength from an FM station broadcasting at 93.9 megahertz on your radio isa. 31.3 mb. 3.13 mc. 0.313 md. 0.0313 me. none of the above

Q: The type of EM radiation that has wavelength just a bit longer than that of visible light is a. ultraviolet b. infrared c. x ray d. microwave e. gamma ray

Q: The type of EM radiation that has wavelength just a bit shorter than that of visible light is a. ultraviolet b. infrared c. x ray d. microwave e. gamma ray

Q: The type of EM radiation emitted when high speed electrons decelerate as they are smashed into a metal target is a. ultraviolet b. infrared c. x ray d. microwave e. gamma ray

Q: Why would a decrease in the amount of ozone in the atmosphere increase the likelihood of people getting sunburn? a. Global temperatures would rise b. More ultraviolet radiation would reach the ground c. People would be exposed to more infrared radiation d. The premise is incorrect. Ozone and sunburn are not related

Q: FM radio only operates in the frequency range 88 MHz to 108 MHz becausea. higher or lower frequencies are blocked by the ionosphereb. higher and lower frequencies are not radio wavesc. the government set those limitsd. none of the above

Q: The type of EM radiation that causes your skin to tan is a. ultraviolet b. infrared c. x rays d. microwave e. gamma rays

Q: The EM wave that has the smallest wavelength in this list is a. ultraviolet b. infrared c. x rays d. microwave e. gamma rays

Q: How do microwave ovens can heat food more quickly than conventional ovens?a. Microwaves give energy directly to the molecules in the food.b. Conventional ovens must conduct heat from the surface to the interior of the food.c. Microwaves heat the inside as well as the surface of the food.d. all of the above

Q: Which of the following is not a common use of microwaves? a. cooking c. radar b. medical imaging d. communications

Q: The highest frequency visible light is a. violet b. red c. blue d. green e. yellow

Q: The lowest frequency visible light is a. violet b. red c. blue d. green e. yellow

Q: The EM wave that has the lowest frequency in this list is a. ultraviolet b. infrared c. x rays d. microwave e. gamma rays

Q: The type of EM wave having the highest frequency is a. ultraviolet b. infrared c. x rays d. microwave e. gamma rays

Q: The type of EM waves used in radar is a. ultraviolet b. infrared c. x ray d. microwave e. blackbody

Q: The radiation emitted from a small hole in a furnace is a. ultraviolet b. infrared c. x ray d. microwave e. blackbody

Q: The main form of radiation that our bodies emit is a. ultraviolet b. infrared c. x ray d. microwave e. blackbody

Q: A superconductor expels any magnetic field from its interior. This is calleda. electromagnetic inductionb. Maxwell's effectc. magnetic declinationd. the Meissner effecte. none of the above

Q: Of the following gases, which is the most important contributor to the Earth's greenhouse effect?a. water vapor b. ozone c. CFCsd. methane

Q: The greenhouse effect is occurring becausea. the ozone layer is being depletedb. the amount of carbon dioxide in the atmosphere is increasingc. the ionosphere reflects low frequency radiationd. more ultraviolet radiation is penetrating the atmospheree. none of the above

Q: The greenhouse effect occurs becausea. low frequency EM waves are reflected from the atmosphereb. high frequency EM waves are reflected from the atmospherec. the ozone layer absorbs ultraviolet lightd. carbon dioxide in the atmosphere absorbs infrared radiatione. none of the above

Q: The ozone layer a. reflects all EM waves b. reflects high frequency radio waves c. reflects low frequency radio waves d. is responsible for the greenhouse effect e. absorbs ultraviolet light in sunlight

Q: The ionosphere a. reflects all EM waves b. reflects high frequency radio waves c. reflects low frequency radio waves d. is responsible for the greenhouse effect e. absorbs ultraviolet light in sunlight

Q: Electromagnetic induction is used in the operation of a. generators b. transformers c. dynamic microphones d. regenerative braking e. all of the above

Q: An iron nail is brought near a magnet. Which of these is nottrue? a. The nail has a north pole and a south pole. b. The nail becomes a north pole or a south pole. c. The magnet exerts an attractive force on the nail. d. The nail exerts an attractive force on the magnet. e. The nail is ferromagnetic.

Q: A magnetic field is created by an electric charge if the charge isa. positiveb. negativec. movingd. stationarye. any of the above

Q: A magnetic field exerts a force on an electric charge if the charge isa. positiveb. negativec. movingd. stationarye. any of the above

Q: The direction of a magnetic field at a point can be determined bya. a generatorb. a compassc. a transformerd. electromagnetic inductione. none of the above

Q: The deviation from the way a compass needle points from the true north direction is thea. greenhouse effectb. magnetic inclinationc. magnetic declinationd. magnetic resonance effecte. none of the above

Q: Thermograms use ultraviolet radiation to sense heat.

Q: The ionosphere can be used to conduct radio communications over long distances.

Q: Higher frequency radio waves are reflected by the ionosphere.

Q: The magnetic compass in an aircraft point to the geographic north pole.

Q: N rays do not exist.

Q: AM radio stations have greater range than FM stations because they have more powerful transmitters.

Q: A coil of wire is connected to a galvanometer. When the coil is rotated in a magnetic field, the galvanometer records a current because the free electrons in the moving wire experience a force from the magnetic field that pushes them through the wire.

Q: A coil of wire is connected to a galvanometer. When a bar magnet is moved in and out of the coil, the galvanometer records a current because of electromagnetic induction.

Q: A body in a room at 300 K is heated to 3,000 K. The wavelength of the most intense EM radiation emitted by the body at 3,000 K is 10 times the wavelength of the most intense EM radiation at 300 K.

Q: A body in a room at 300 K is heated to 3,000 K. The amount of energy radiated each second by the body increases 10,000 times.

Q: The peak of a body's blackbody radiation curve shifts upward as the temperature of the body increases.

Q: The peak of a body's blackbody radiation curve shifts toward longer wavelength as the temperature of the body increases.

Q: As the temperature of a body increases the color of the body shifts from blue to red.

Q: If the Kelvin temperature of a body is doubled, the wavelength of the most intense light is double the wavelength originally of the most intense light.

Q: As the temperature of an object increases, the wavelength of the brightest light emitted increases.

Q: NARRBEGIN: Body emitting blackbodyFor a body emitting blackbody radiation, the total power emitted is proportional to the 4th power of the body's absolute temperature:(Tin kelvins)and the wavelength of the emitted EM radiation that has the highest intensity is inversely proportional to the body's absolute temperature according to:( in meters, Tin kelvins)Assume an object is emitting blackbody radiation.NARRENDIf the Kelvin temperature of an object is doubled, the amount of radiant energy emitted each second is twice the original amount.

Q: A changing magnetic field produces an electric field.

Q: The cosmic background radiation corresponds to a blackbody at a temperature of 2.726 kelvins.

Q: The wavelength of a radio wave from an FM station broadcasting at 93.9 megahertz on your radio dial is 0.313 meters.

Q: An electric motor on an airplane operates on 24 volts and draws a current of 15 amperes. (a) What is the power consumption of the motor? (b) How much energy does the motor use during a 2 hour flight?

Q: How much energy does a 100 watt light bulb use in 1 hour? Express your answer in (a) joules and in (b) kilowatt-hours. (c) Also find how much money it costs if electricity sells for 10 cents per kW-h.

Q: The light bulb used in a slide projector draws a current of 4 amperes when operating on 120 volts. (a) What is the bulb's resistance? (b) What is the bulb's power consumption?

Q: An electric toaster operating on 120 volts draws a current of 9 amperes. What is the resistance of the toaster?

Q: A battery in a large flashlight produces a current of 2 amperes in a light bulb that has a resistance of 3 ohms. What is the voltage of the battery?

Q: Match each item with the correct statement below.a. AC i. repelb. attract j. resistancec. critical temperature k. semiconductord. electric current l. transformere. DC m. superconductorf. electric field n. voltageg. negative ion o. electric chargeh. positive ion p. ohmic heating1/ superconductivity is lost when this is exceeded2/ an atom with fewer electrons than protons3/ type of current supplied by a battery4/ employed in toasters and fuses5/ has zero resistance6/ consists of charges flowing back and forth7/ rate of flow of electric charge8/ used to change AC voltages9/ the energy per unit charge supplied by a battery10/ like charges do this11/ it is measured in ohms12/ this phenomenon results in a loss of usable energy

Q: A simple electrical circuit has a constant voltage power supply and a variable resistor as a circuit. As you increase the resistance the current flow _______________.

Q: In a thunderstorm cloud, the concentration of negative charge is in the __________ portion of the cloud.

Q: The loss of usable energy in cables used to conduct electricity from power plants to citeis is cause by ________________.

Q: The energy used by a 100 watt light bulb in 1 hour is __________.

Q: If two slide projectors are connected in series across the same 120 volt source, the current drawn from the source is __________.

Q: If two slide projectors are connected in parallel across the same 120 volt source, the current drawn from the source is __________.

Q: The power consumed by the light bulb is __________.

Q: NARRBEGIN: Lightbulb slide projectorA light bulb used in a slide projector draws a current of 6 amperes when operating on 120 volts.NARRENDThe resistance of the light bulb is __________.

Q: An electric toaster operating on 120 volts draws a current of 6 amperes. The resistance of the toaster is __________.

Q: A battery operating a large flashlight produces a current of 2 amperes in a light bulb that has a resistance of 4 ohms. The voltage of the battery is __________.

Q: When a 12 volt car battery is short circuited with a wire, the current drawn from the battery is 100 amperes. The resistance of the wire is __________.

Q: AC voltages can be easily increased or decreased through use of a __________.

Q: If the voltage across the ends of a wire increases, the current in the wire __________.

Q: If the temperature of a wire increases, its resistance __________.

Q: If the diameter of a wire increases, its resistance __________.

Q: If the length of a wire increases, its resistance __________.

Q: Four things that the resistance of a conducting material depends on are __________, __________, __________ and ___________.

Q: Two charged bodies separated by a distance d exert an attractive electrical force on each other. The signs of the charges on the two bodies are __________ and __________.

Q: Two charged bodies separated by a distance d exert an electrical force on each other. The distance d is doubled. The electrical force on each body is now __________ times the original force.

Q: The force on a charged object divided by the charge on the object is __________.

Q: If you think of a battery as an electric charge "pump," the battery voltage is analogous to __________.

Q: The size of the current flowing through a conductor equals the __________ divided by the conductor's ___________.

Q: A quantity that measures the opposition to the flow of charge is __________.