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All Textbook Solutions for Conceptual Physics: The High School Physics Program
If the resistance of a circuit remains constant while the voltage across the circuit decreases to half its former value, what change occurs in the current?If the voltage impressed across a circuit is constant but the resistance doubles, what change occurs in the current?How does wetness affect the resistance of your body?Why is it that a bird can perch without harm on a high-voltage wire?What is the function of the third prong in a household electric plug?Distinguish between DC and AC. Which is produced by a battery and which is usually produced by a generator?A diode converts AC to pulsed DC. What electric device smooths the pulsed DC to a smoother DC?What are the roles of a diode and a capacitor in an AC–DC converter?What is a typical 'drift' speed of electrons that make up a current in a typical DC circuit? In a typical AC circuit?From where do the electrons originate that flow in a typical electric circuit?What is power?Which of these is a unit of power and which is a unit of electrical energy: a watt, a kilowatt, and a kilowatt-hour?How many amperes flow through a 60-watt bulb when 120 volts are impressed across it?Rank the circuits below according to the brightness of the bulbs, from brightest to dimmest.The bulbs shown below are identical. An ammeter is placed in different branches, as shown. Rank the current readings in the ammeter from greatest to least.All bulbs are identical in the circuits shown below. An ammeter is connected next to the battery as shown. Rank the current readings in the ammeter, from greatest to least.In each of the circuits shown below, a voltmeter is connected across a bulb to measure the voltage drop across it. Rank the voltage readings from greatest to least.All bulbs are identical in the circuit shown to the right. The circuit consists of three parts: (A) the top branch with two bulbs; (B) the middle branch with one bulb; and (C) the battery. a. Rank the current through A, B, and C, from greatest to least. b. Rank the voltage across A, B, and C, from greatest to least.Calculate the current where 10 coulombs of charge pass a point in 5 seconds.Calculate the current of a lightning bolt that delivers a charge of 35 coulombs to the ground in a time of 1/1000 second.Calculate the current in a toaster that has a heating element of 14 ohms when connected to a 120-V outlet.Calculate the current in the coiled heating element of a 240-V stove. The resistance of the element is 60 ohms at its operating temperature.Electric socks, popular in cold weather, have a 90-ohm heating element that is powered by a 9-volt battery. How much current warms your feet?How much current moves through your fingers (resistance: 1200 ohms) if you touch them to the terminals of a 6-volt battery?Calculate the power supplied to an electric blanket that carries 1.20 A when connected to a 120-V outlet.Is this label on a household product cause for concern? 'Caution: This product contains tiny electrically charged particles moving at speeds in excess of 10,000,000 kilometers per hour.'Do an ampere and a volt measure the same thing, or different things? What are those things, and which is a flow and which is the cause of the flow?What happens to the brightness of light emitted by a light bulb when the current in it increases?In terms of heating, why are thick wires rather than thin wires used to carry large currents?Why is it important that the resistance of an extension cord be small when it is used to power an electric heater?Why will an electric drill operating on a very long extension cord not rotate as fast as one operated on a short cord?Your tutor tells you that an ampere and a volt really measure the same thing, and the different terms only serve to make a simple concept seem confusing. Why should you consider getting a different tutor?Does more current flow out of a battery than into it? Does more current flow into a lightbulb than out of it? Explain.A simple lie detector consists of an electric circuit, one part of which is part of your body. A sensitive meter shows the current that flows when a small voltage is applied. How does this technique indicate that a person is lying? (And when does this technique not indicate when someone is lying?)Only a small fraction of the electric energy fed into a common lightbulb is transformed into light. What happens to the rest?Will a lamp with a thick filament draw more current or less current than a lamp with a thin filament made of the same material?49AWill the current in a lightbulb connected to 220 V be more or less than when the bulb is connected to 110 V? How much?Which will do more damage—plugging a 110-V toaster into a 220-V circuit or plugging a 220-V toaster into a 110-V circuit? Explain.If current of one- or two-tenths of an ampere were to flow into one of your hands and out the other, you would probably be electrocuted. But if the same current were to flow into your hand and out the elbow above the same hand, you could survive, even though the current might be large enough to burn your flesh. Explain.What is the effect on current if both the voltage and the resistance are doubled? If both are halved?In 60-Hz alternating current, how many times per second does an electron change its direction? (Dont say 60!)If electrons flow very slowly through a circuit, why doesnt it take a noticeably long time for a lamp to glow when you turn on a distant switch?What unit is represented by (a) joule per coulomb, (b) coulomb per second, and (c) watt-second?Two lightbulbs designed for 120-V use are rated at 40 W and 60 W. Which light-bulb has the greater filament resistance? Why?A cars headlights dissipate 40 W on low beam and 50 W on high beam. Is there more or less resistance in the high-beam filament?How much current, in amperes, is in a lightning stroke that lasts 0.05 second and transfers 100 coulombs?How much charge flows in a pocket calculator each minute when the current is 0.0001 ampere?How much voltage is required to make 2 amperes flow through a resistance of 8 ohms?Use the relationship power=currentvoltage to find out how much current is drawn by a 1200-watt hair dryer when it operates on 120 volts. Then use Ohms law to find the resistance of the hair dryer.The current driven by voltage V in a circuit of resistance R is given by Ohms law, I=V/R. Show that the resistance of a circuit carrying current I and driven by voltage V is given by the equation R=V/I.Use the equation just derived and show that when a device in a 120-V circuit draws a current of 20 A, its resistance is 6.The power of an electric circuit is given by the equation P=IV. Use Ohms law to express V and show that power can be expressed by the equation P=I2R.An electric heater has a heating element of resistance 12. It is plugged into a wall socket that provides 120 V. a. What is the current through the heater? b. What is the power 'consumption' of the heater?Calculate the resistance of the filament in a lightbulb that carries 0.4 A when 3.0 V is impressed across it.A lightbulb is marked ' 120 V, 60 W.' a. What current flows through the filament when the bulb is turned on? b. Show that the electrical resistance of the lightbulb filament is 240.A microwave oven is marked '120 V, 1100 w.' a. How much current does the oven draw? b. To heat 380 g of 20C water to 86C show that you should set the timer for at least 95 s.A typical car headlight may put out 50 watts at 12 volts. a. Show that 4.2 A is drawn by the headlight. b. How many electrons pass through the bulb filament each second?Suppose that an ammeter inserted in series in a toaster circuit shows that the current is 5.0 amps when the toaster is plugged into a 120-volt circuit. Show that the energy dissipated by the toaster in 40 seconds is 24,000 joules.The wattage marked on a lightbulb is not an inherent property of the bulb but depends on the amount of voltage to which it is connected, usually 110 V or 120 V. a. Calculate the Current through a 40-W bulb connected to 120 V. b. Calculate the current through the same bulb when it is connected to 60 V.The resistance of a certain wire is 10 ohms. a. What would the resistance of the same wire be if it were twice as long? b. If it had twice the diameter?Calculate the power dissipated in a toaster that has a resistance of 14 ohms and is plugged into a 120-V outlet.Calculate the yearly cost of running a 5-W electric clock continuously in a location where electricity costs 10 cents per kWh.Are all the electrons flowing in a circuit provided by the battery?Why must there be no gaps in an electric circuit for it to carry current?Distinguish between a series circuit and a parallel circuit.If three lamps are connected in series to a 6-volt battery, how many volts are impressed across each lamp?If one of three lamps blows out when connected in series, what happens to the current in the other two?If three lamps are connected in parallel to a 6-volt battery, how many volts are impressed across each lamp?If one of three lamps blows out when connected in parallel, what happens to the current in the other two?a. In which case will there be more current in each of three lamps—if they are connected to the same battery in series or in parallel? b. In which case will there be more voltage across each lamp?What happens to the total circuit resistance when more devices are added to a series circuit? To a parallel circuit?What is the equivalent resistance of a pair of 8-ohm resistors in series? In parallel?Why does the total circuit resistance decrease when more devices are added to a parallel circuit?What does it mean when you say that lines in a home are overloaded?What is the function of a fuse or circuit breaker in a circuit?Why will too many electric devices operating at one time often blow a fuse or trip a circuit breaker?What is meant by a short circuit?The resistors in the circuits below are all identical. Rank the circuits according to the size of the equivalent resistance for each, from most resistance to least resistance.The circuit below contains resistors R1, R2, and R3. Rank the following combinations of resistances in terms of the current measured by the ammeter, from highest to lowest. (A) R1=1,R2=2,R3=3 (B) R1=2,R2=1,R3=2 (C) R1=3,R2=3,R3=1The resistors in the circuits below are 10 each. Each circuit is powered with a 12-V battery. Assume that the battery and connecting wires have negligible resistance. a. Rank the circuits in terms of the amount of current passing point P in each circuit, from greatest current to least current. b. Suppose a voltmeter is connected between point P and the negative terminal of the battery. Rank the circuits in terms of voltmeter readings, from highest voltage to lowest voltage.Calculate the equivalent resistance of two 6- resistors in series.Calculate the equivalent resistance (using the product-over-sum' rule) of a pair of 6- resistors in parallel.Calculate the current in a 12-V battery that powers a single 30- resistor.Calculate the current in a 12-V battery that powers three 30- resistors connected in series.Calculate the current in a 48-V battery that powers a pair of 30- resistors connected in series.Calculate the current in a 48-V battery that powers a pair of 30- resistors connected in parallel.One example of a water system is a garden hose that waters a garden. Another is the cooling system of an automobile. Which of these exhibits behavior more analogous to that of an electric circuit? Why?Sometimes you hear someone say that a particular appliance 'uses up' electricity. is it that the appliance actually 'uses up,' and what becomes of it?Why are the wingspans of birds a consideration in determining the spacing between parallel wires in a power line?Your lab partner says that a battery provides not a source of constant current, but a source of constant voltage. Do you agree or disagree, and why?Will the current in a lightbulb connected to a 220-V source be greater or less than that in the same bulb when it is connected to a 110-V source?To connect a pair of resistors so that their equivalent resistance will be greater than the resistance of either one, should you connect them in series or in parallel?To connect a pair of resistors so that their equivalent resistance will be less than the resistance of either one, should you connect them in series or in parallel?Hector says that adding bulbs in series to a circuit provides more obstacles to the flow of charge, reducing current in the circuit. Jeremy says that adding bulbs in parallel provides more paths so more current can flow. With whom do you agree or disagree?Consider a pair of flashlight bulbs connected to a battery. Emily asks if they glow brighter when connected in series, or in parallel. She looks to you for an answer. What is your answer?Harry asks whether a battery will run down slower or faster when it connects to a pair of bulbs in series or to the same pair in parallel. He looks to you for an answer. What is your answer?As more and more lamps are connected in series to a flashlight battery, what happens to the brightness of each lamp?As more and more lamps are connected in parallel to a battery, and if the current does not produce heating inside the battery, what happens to the brightness of each lamp?If several bulbs are connected in series to a battery, they may feel warm to the touch even though they are not visibly glowing. What is your explanation?Are automobile headlights wired in parallel or in series? What is your evidence?Why are household appliances almost never connected in series?In the circuit shown, how do the brightnesses of the identical bulbs compare? Which lightbulb draws the most current? What happens if bulb A is unscrewed? If bulb C is unscrewed?A number of lightbulbs are to be connected to a battery. Which will provide more overall brightness, connecting them in series or in parallel? Which will run the battery down faster, the bulbs connected in series or the bulbs connected in parallel?Are these circuits equivalent to one another? Why or why not?A battery has internal resistance, so if the current it supplies goes up, the voltage it supplies goes down. If too many bulbs are connected in parallel across a battery, will their brightness diminish? Explain.A three-way bulb uses two filaments to produce three levels of illumination (50 W, 100 W, and 150 W) using a 120-V socket. When one of the filaments burns out, only one level of illumination (50 W or 100 W) is available. Are the filaments connected in series or in parallel?How does the line current compare with the total currents of all devices connected in parallel?Your friend says that electric current takes the path of least resistance. Why is it more accurate in the case of a parallel circuit to say that greatest current travels in the path of least resistance?A 60-W bulb and a 100-W bulb are connected in series in a circuit. a. Which bulb has the greater current flowing in it? b. Which has the greater current when they are connected in parallel?A 30- resistor is connected to a 240-V source. How much current flows in the resistor?A lightbulb connected to a 3.0-V battery draws 1.2 A of current. Calculate the resistance of the bulb.A lantern battery is connected to a 4- device that draws 1.5 A. Calculate the battery voltage.A 16- loudspeaker and an 8- loudspeaker are connected in parallel across the terminals of an amplifier. Assuming the speakers behave as resistors, calculate the equivalent resistance of the two speakers.Consider the combination series and parallel circuit shown here. a. Identify the parallel part of the circuit. What is the equivalent resistance of this part? In other words, what single resistance could replace this part of the circuit and not change the total current from the battery? b. What is the equivalent resistance of all the resistors? In other words, what single resistance could replace the whole circuit without changing the current produced by the battery?How many 4- resistors must be connected in parallel to create an equivalent resistance of 0.5?What is the current in the battery of the circuit shown below? (What must you find before you can calculate the current?)The rear window defrosters on automobiles are made up of several strips of heater wire connected in parallel. Consider the case of four wires, each of 6 resistance, connected to 12 V. a. What is the equivalent resistance of the four wires? (Consider the wires to be two groups of two.) b. What is the total current drawn?56AThe same voltage V is impressed on each of the branches of a parallel circuit. The voltage source provides a total current Itoal to the circuit, and sees' a total equivalent resistance of R in the circuit. That is, V=ItotalReq. The total current is equal to the sum of the currents through each branch of the parallel circuit. In a circuit with n branches, Itoal=I1+I2+I3...In .Use Ohms law I=V/R and show how the equivalent resistance of a parallel circuit with n branches is given by the following equation. 1Req=1R1+1R2+1R3+1RnShow how the expression given in Question 57, when applied to two branches with resistances R1 and R2, can be written as follows. Req=R1R2R1+R2Obtain several drinking straws. Take a deep breath and then fully exhale through one of the straws. Note the time it takes to do this. Repeat, fully exhaling through a pair of straws side by side. Can you exhale in less time? Try with three side-by-side straws. How does this relate to resistors in parallel in electric circuits?1A2A3A4AWhat is so special about iron that makes each iron atom a tiny magnet?What is a magnetic domain?7AHow can a piece of iron be induced into becoming a magnet? For example, if you place a paper clip near a magnet, it will itself become a magnet. Why?9A10AIf a current-carrying wire is bent into a loop, why is the magnetic field stronger inside the loop than outside?12A13A14AHow does the direction in which a current-carrying wire is forced when in a magnetic field compare with the direction that moving charges are forced?How do the concepts of force, field, and current relate to a galvanometer?Why is it important that the current in the armature of a motor that uses a permanent magnet periodically change direction?What is meant by magnetic declination?19AWhat are magnetic pole reversals, and what evidence is there that Earths magnetic field has undergone pole reversals throughout its history?The electromagnets A, B, and C are shown below. Note the number of turns of wire and the current in each. The iron cores are Identical. Rank the electromagnets in magnetic field intensity at point P (just outside each electromagnet), from strongest to weakest.Three pairs of electromagnets made with identical iron cores are shown below. Note the number of turns of wire, each of which carries the same current. a. Rank the electromagnet pairs A, B, and C in terms of the force between the electromagnets, from most attractive to most repulsive. b. Rank the electromagnet pairs A, B, and C in terms of the magnitude of the magnetic field at the exact midpoint between the electromagnets.Since every iron atom is a tiny magnet, why arent all iron materials themselves magnets?An electron always experiences a force in an electric field, but not always in a magnetic field, Defend this statement.What kind of field surrounds a stationary electric charge? A moving electric charge?Why can iron be made to behave as a magnet while wood connot?27AA friend tells you that a refrigerator door, beneath a layer of white-painted plastic, is made of aluminum. How could you check to see if this is true (without any scraping)?Since iron filings are not themselves magnets, by what mechanism do they align themselves with a magnetic field as shown in Figure 36.6?30AA strong magnet and a weak magnet attract each other. Which magnet exerts the stronger force—the strong one or the weak one? (Could you have answered this using what learned In Chapter 6?)32AWhy will the magnetic field strength be further increased inside a current-carrying coil if a piece of iron is placed in the coil?Can an electron be set into motion with a magnetic field? With an electric field?In what direction relative to a magnetic field a charged particle travel in order to experience maximum magnetic force? Minimum magnetic force?When a current-carrying wire is placed in a strong magnetic field, no force acts on the wire. What orientation of the wire is likely?A magnetic field can deflect a beam of electrons, but it cannot do work on them to speed them up. Why? (Hint: Consider the direction of the force relative to the direction in which the electrons move.)A cyclotron is a device for accelerating charged particles to high speeds in circular orbits of ever-increasing radius. The charged particles are subjected to both an electric field and a magnetic field. One of these fields increases the speed of the particles, and the other field holds them in a circular path. Which field performs which function?By present-day custom, the direction of electric current is the direction in which positive charge flows. The direction of a magnetic field surrounding a current- carrying wire can be shown by what is called the 'right-hand rule.' Wrap your right-hand fingers around a current-carrying wire in such a way that your thumb points in the direction of the electric current; then your fingers point in the direction of the magnetic field. Suppose instead that the current direction were defined as the direction in which electrons move in the wire. Why then would a 'left-hand rule' be used for identifying magnetic field direction?40AHow do the input and output parts of a generator and a motor compare?Your friend says that if you crank the shaft of a DC motor manually, the motor becomes a DC generator. Do you agree or disagree? Defend your position.Residents of northern Canada are bombarded by more intense cosmic radiation than are residents of Mexico. Why is this so?What changes in cosmic ray intensity at Earths surface would you expect during periods in which Earths magnetic field passed through a zero phase while undergoing pole reversals? (A speculation supported by fossil evidence is that the periods of no protective magnetic field may have been as effective in changing life forms as X-rays have been in the famous heredity studies of fruit flies.)Earths core is probably composed of iron and nickel, excellent metals foe making permanent magnets. Why is it unlikely that Earths core is a permanent magnet?An iron bar can be easily magnetized by aligning it with the magnetic field lines of Earth and striking it lightly a few times with a hammer. This works best if the bar is tilted down to match the dip of Earths field. The hammering jostles the domains so they can better fall into alignment with Earths field. The bar can be demagnetized by striking it when it is in an east—west direction.What did Michael Faraday and Joseph Henry discover?How can voltage be induced in a wire with the help of a magnet?A magnet moved into a coil of wire will induce voltage in the coil. What is the effect of moving a magnet into a coil with more loops?Why is it more difficult to move a magnet into a coil of more loops that is connected to a resistor?Current, as well as voltage, can be induced in a wire by electromagnetic induction. When can voltage be induced but not current?How does the frequency of a changing magnetic field compare with the frequency of the alternating voltage that is induced?What is a generator, and how does it differ from a motor?Why is the voltage induced in an alternator AC rather than DC?The armature of a generator must rotate in order to induce voltage and current. What produces the rotation?A motor is characterized by three main ingredients: magnetic field, moving charges, and magnetic force. What are the three main ingredients that characterize a generator?What does a transformer actually transform—voltage, current, or energy?What does a step-up transformer step up—voltage, current, or energy?How does the relative number of turns on the primary and the secondary coil in a transformer affect the step-up or step-down voltage factor?If the number of secondary turns is 10 times the number of primary turns, and the input voltage to the primary is 6 volts, how many volts will be induced in the secondary coil?15AWhy is it advantageous to transmit electric power long distances at high voltages?What fundamental quantity underlies the concepts of voltages and currents?Distinguish between Faradays law expressed in terms of fields and Maxwells counterpart to Faradays law. How are the two laws symmetrical?How do the wave speeds compare for high-frequency and low-frequency electromagnetic waves?20AThe magnets are moved into the wire coils in identical quick fashion. Voltage induced in each coil causes a current to flow, as indicated on the galvanometer. Neglect the electrical resistance of the loops in the coil. a. Rank from greatest to least the reading on the galvanometer. b. Make the same ranking, only this time for each coil having twice as many loops as in part (a).The transformers are all powered with 100 W, and all have 100 turns on the primary. The number of turns on each secondary varies as shown. a. Rank the voltage output of the secondaries from greatest to least. b. Rank the current in the secondaries from greatest to least. c. Rank the power output in the secondaries from greatest to least.When Tim pushes the wire down between the poles of the magnet, the galvanometer registers a pulse. When he lifts the wire, another pulse is registered. How do the pulses differ?A common pickup for an electric guitar consists of a coil of wire around a permanent magnet. The permanent magnet magnetizes the nearby guitar string. When the string is plucked, it oscillates above the coil, thereby changing the magnetic field that passes through the coil. The rhythmic oscillations of the string produce the same rhythmic changes in the magnetic field in the coil, which in turn induce the same rhythmic voltages in the coil, which when amplified and sent to a speaker produce music! Why will this type of pickup not work with nylon strings?Two separate but similar coils of wire are mounted close to each other, as shown below. The first coil is connected to a battery and has a direct current flowing through it. The second coil is connected to a galvanometer. How does the galvanometer respond when the switch in the first circuit is closed? When the current is steady after the switch is closed? When the switch is opened?If you place a metal ring in a region in where a magnetic field is rapidly alternating, the ring may become hot to your touch. Why?A magician places an aluminum ring on a table, underneath which is hidden an electromagnet. When the magician says 'abracadabra' (and pushes a switch that starts current flowing through the coil under the table), the ring jumps into the air. Explain his trick.How could you light a lightbulb that is near, yet not touching, an electromagnet? Is AC or DC required? Defend your answer.What is the basic difference between an electric generator and an electric motor?With no magnets around, why will current flow in a coil of wire waved around in the air?What is the source of all electromagnetic waves?Why is a generator armature more difficult to rotate when it is connected to and supplying electric current to a circuit?Your classmate says that, if you crank the shaft of a conventional motor manually, the motor becomes a generator. Do you agree or disagree, and why?Some bicycles have electric generators that are made to turn when the bike wheel turns. These generators provide energy for the bikes lamp. Will a cyclist coast farther if the lamp connected to the generator is turned off? Explain.An electric hair drier running at normal speed draws a relatively small current. But if somehow the motor shaft is prevented from turning, the current dramatically increases and the motor overheats. Why?When a piece of plastic tape coated with iron oxide that is magnetized more in some parts than others is moved past a small coil of wire, what happens in the coil? What is a practical application of this?Why is it important that the core of a transformer pass through both coils?Why can a hum often be heard when a transformer is operating?When a strip of magnetic material, variably magnetized, is embedded in a plastic card that is moved past a small coil of wire, what happens in the coil? What is a practical application of this?If a car made of iron and steel moves over a wide closed loop of wire embedded in a road surface, will the magnetic field of Earth in the loop be altered? Will this produce a current pulse? (Can you think of a practical application of this?)41AHow could you move a conducting loop of wire through a magnetic field without inducing a voltage in the loop?Why does a transformer require alternating voltage?How does the current in the secondary of a transformer compare with the current in the primary when the secondary voltage is twice the primary voltage?In what sense can a transformer be thought of as an electrical lever? What does it multiply? What does it not multiply?Can an efficient transformer step up energy? Defend your answer.A friend says that changing electric and magnetic fields generate one another, and this gives rise to visible light when the frequency of change matches the frequencies of light. Do you agree? Explain.Would electromagnetic waves exist if changing magnetic fields could produce electric fields but changing electric fields could not in turn produce magnetic fields? Explain.When a bar magnet is dropped through a vertical length of copper pipe, it falls noticeably more slowly than it does when it is dropped through a vertical length of plastic pipe. If the copper pipe is long enough, the dropped magnet will reach a terminal falling speed. Propose an explanation.What is wrong with this scheme? To generate electricity without fuel, arrange a motor to run a generator that will produce electricity that is stepped up with transformers so that the generator can run the motor and simultaneously furnish electricity for other uses.An electromagnet A with a coil of 10 turns carrying I A interacts with electromagnet B, which has 100 turns carrying 2 A, Which electromagnet exerts the greater force on the other?An electric doorbell requires 12 volts to operate correctly. A transformer nicely allows it to be powered from a 120-volt outlet. If the primary has 500 turns, show that the secondary should have 50 turns.A model electric train requires 6 V to operate. When connected to a 120-V house-hold circuit, a transformer is needed. If the primary coil of the transformer has 240 windings, show that there should be 12 turns in the secondary coil.If the output current for the above transformer is 1.8 amps, show that the input current is 0.09 A.A transformer has an input of 9 volts and an output of 36 volts. If the input is changed to 12 volts, show that the output would be 48 volts.A model electric train requires a low voltage to operate. If the primary coil of its transformer has 400 turns, and the secondary has 40 turns, how many volts will power the train when the primary is connected to a 120-volt household circuit?57A58ANeon signs require about 12,000 V for their operation. What should be the ratio of the number of loops in the secondary to the number of loops in the primary for d neon-sign transformer that operates off 120-V lines?What is a model? Give two examples for the nature of light.2A3A4A5A6A7A8A9AWhat causes light to behave like a particle?11A12A13A14A15A16A17A18AWhy are the heaviest elements not appreciably larger than the lightest elements?20A21AWhat information is necessary to make predictions about an orderly system?23A24A25A26A27A28A29A30A31A32A33A34A35A36A37A38A39A40AWhy will helium leak through an inflated rubber balloon more readily than hydrogen will?1A2A3AWhich force has a longer range, the electric force or the strong force?5A6A7A8A9A10AWhat is meant by radioactive half-life?If the radioactive half-life of a certain isotope is 1620 years, how much of that substance will be left at the end of 1620 years? After 3240 years?When an atom undergoes radioactive decay, does it become a completely different element?14A15A16A17AWhich is radioactive, C-12 or C-14?Why is more C-14 found m new bones than in ancient bones of the same mass?20AWhy are there deposits of lead in all deposits of uranium ore?What isotopes accumulate in old, uranium-bearing rock?What is a radioactive tracer?From where does most of the radiation you encounter originate?Why is radiation more intense at high altitudes and near Earths poles?Rank these three types of radiation by their ability to penetrate this page of your book: (A) Alpha particle (B) Beta particle (C) Gamma ray27A28AConsider two 100-gram samples of radium-226 and uranium-238. Rank by the amount left of each. (A) radium after 1620 years (B) uranium after 2 half-lives (C) radium after 3 half-lives (D) uranium after 1 half-life30AIs radioactivity in the world something relatively new? Defend your answer.In the nineteenth century, the famous physicist Lord Kelvin made measurements of heat transfer in Earths crust and estimated Earths age to be very much less than the present estimate. What information did Kelvin not have that might have allowed him to avoid making his erroneous estimate?