PHYS 1060 Spring 2012

A low-pressure sodium-vapor lamp emits yellow light. What aspect of the lamp causes it to emit that particular yellow light?

(A) That yellow light is determined by the temperature at which sodium metal vaporizes to become sodium gas and begins to emit light.

(B) That yellow light is determined by the frequency of the electron cloud as quantum physics allows it to tunnel into the nucleus.

(C) That yellow light is determined by the wavelength of a sodium atom as its quantum wave undergoes stimulated emission.

(D) That yellow light is determined by the energy released when an electron in a sodium atom makes a radiative transition from an excited orbital to a ground-state orbital.

You are cooking for a charity event and you flip a pancake straight up, high above the frying pan. Disregarding any effects due to the air, what force or forces are acting on the pancake while it is above the frying pan?

(A) A steadily decreasing upward force from the moment it leaves the frying pan until it reaches its highest point and then a steadily increasing downward force as the pancake returns toward the pan.

(B) Its weight along with a steadily decreasing upward force.

(C) Its weight along with an upward force that steadily decreases until the pancake reaches its highest point. After that point, there is only the constant downward force of gravity.

(A) water molecules have a large net pole.

(B) water molecules have a large magnetic dipole (a north pole and a south pole).

(D) water molecules have a large net charge.

A strong bar magnet has one north pole and one south pole. The magnet falls into a meat grinder at the delicatessen, and is reduced to tiny pieces of bar magnet. You collect several pieces of what was the bar magnet's north pole and also several pieces of what was its south pole. You examine those pieces and find that

(A) each piece is randomly a north pole or a south pole. It doesn't matter which part of the bar magnet each piece came from.

(B) pieces of the north pole are north poles and pieces of the south pole are south poles.

(D) pieces of the north pole are south poles and pieces of the south pole are north poles.

Of the following types of electromagnetic waves, the type that has the highest energy per photon is

On a sunny day, you can use a circular magnifying glass to burn wood by focusing the sun's light to a small spot on the wood. Light from the sun reaches the magnifying glass, bends as it passes through the lens, and forms a small round, brilliant spot of light on the wood. The spot of light is round is because

(A) it is a real image of the round sun itself. The magnifying glass behaves like a camera lens.

(B) the magnifying glass is round. A square magnifying glass would create a square spot of light.

(C) a focus means that all light passing through the lens is brought together to a single point in space. A single point always looks round.

(D) particles of light (photons) are spherical and, when brought together at a focus, form a circular spot.

(A) its surface layer is almost pure quartz glass, which is stronger than soda-lime-silica glass.

(B) it contains martensite crystals, which are much harder than ordinary ferrite crystals.

(D) its surface layer is compressed by the tense core of the glass.

At room temperature, natural rubber (from a rubber tree) is a bouncy, elastic solid. If you heat it in boiling water, however, it melts into a gooey liquid. Why is this rubber solid at room temperature?

(A) Its clingy molecules bind together to prevent any local movement.

(B) Its long molecules are too tangled to pull apart.

(D) Its rod-like molecules form crystals at room temperature and those crystal are solid.

The transformer in advertizing sign has 120 turns in its primary coil and 480 turns in its secondary coil. With 120 volt AC power connected to the primary coil and a current of 1 ampere flowing through that primary coil, the transformer's secondary coil is supplying

(A) 30 volt AC power and a current of 4 ampere is flowing through that secondary coil.

(B) 30 volt AC power and a current of 1/4 ampere is flowing through that secondary coil.

(D) 480 volt AC power and a current of 4 amperes is flowing through that secondary coil.

A lead bell emits a dull "thump" sound at room temperature. When cooled in liquid nitrogen, however, it rings like a musical instrument. How does cooling the lead bell make it so musical?

(A) At low temperatures, the lead's mass decreases and its pitch shifts into the audible range.

(B) At low temperatures, the lead's mass increases and its pitch shifts into the audible range.

(D) At low temperatures, the lead crystals cannot change shape permanently and they act like springs.

Suppose that you have purchased a fluorescent lamp that was accidentally manufactured without the white coating on the inside of its glass tube. You can see right through the glass tube, which appears empty. When you turn that lamp on, it will emit

(A) a dim bluish glow.

(B) brilliant white light from a thin line down the center of the glass tube.

(D) no light at all.

Plastic milk jugs are made of high-density polyethylene (HDPE). The wax-like molecules of HDPE are simple carbon chains, decorated only with hydrogen atoms. Why is HDPE a translucent (cloudy) plastic?

(A) The surface of HDPE is rough and that textured surface gives the plastic a cloudy appearance.

(B) HDPE has countless individual molecules and those individual molecules disturb the light as it passes through the plastic.

(D) HDPE is partly crystalline and partly non-crystalline, and light partially reflects from each crystal surface in the plastic.

An electromagnet is a coil of wire that becomes magnetic due to electricity. What aspect of electricity makes it magnetic?

(A) Electric polarization is magnetic.

(B) Electric current is magnetic.

(D) Electric voltage is magnetic.

You are at the gym, exercising on a step machine. You have one foot on each of the machine's pedals and you move those pedals up and down as you step. The pedals always push upward on your feet, but they push harder while moving downward than while moving upward. When during this exercise is your foot transferring energy to the pedal that it is touching?

(A) As that pedal moves either upward or down.

(B) When that pedal is accelerating.

(D) As that pedal moves downward.

A DVD player uses a laser beam to read a DVD disc. To form the smallest possible light spot on the disc's information layer, the DVD player focuses the laser beam using a converging lens that has a

(A) small diameter and a short focal length.

(B) small diameter and a short focal length.

(D) large diameter and a short focal length.

Ordinary (not stainless) steel can be hardened by heat treatment if it contains what element besides iron?

(A) it is too dense to melt.

(B) it is essentially a single giant molecule and cannot melt.

(D) it is too heavy to melt.

A fairy-tale prisoner in a deep dungeon is trapped below a flat glass plate several feet thick. A narrow ray of white sunlight makes its way through the dense, dark forest above the dungeon and strikes the top of the glass plate at an angle. Most of that light emerges into the prisoner's cell from the bottom of the plate, but it is spread out into a rainbow of color. What real-world effect has separated the white ray of light into its constituent colors?

(A) The violet end of the spectrum refracted (bent) more sharply when entering the glass than did the red end of the spectrum.

(B) Violet light traveling through the glass experienced destructive interference while red light traveling through the glass experienced constructive interference.

(C) The violet end of the spectrum refracted (bent) less sharply when entering the glass than did the red end of the spectrum.

(D) Violet light traveling through the glass experienced constructive interference while red light traveling through the glass experienced destructive interference.

If the speed of light in water did not depend on the wavelength of that light, a rainbow would

(A) still appear red on the outside and violet on the inside.

(D) not appear at all.

Separating uranium-235 atoms from uranium-238 atoms is extremely difficult because both atoms have the same number of

(A) neutrons and therefore have identical weights.

(B) electrons and are therefore chemically identical.

(D) protons and therefore have identical masses.

Your flashlight is switched on and a wire inside it is carrying current from the positive battery terminal to the lamp input. Compare the voltage at the positive battery terminal to the voltage at the lamp input.

(A) The voltage at the positive battery terminal is equal to the voltage at the lamp input, but not zero.

(B) The voltage at the positive battery terminal is slightly less than the voltage at the lamp input.

(D) The voltages at both the positive battery terminal and the lamp input are zero.

Electric power is transmitted long distances as a relatively small current at a relatively high voltage because the power wasted in the transmission wires is

(A) inversely proportional to the square of the voltage (i.e., proportional to 1/voltage^2), so increasing that voltage dramatically reduces the wasted power.

(B) inversely proportional to the voltage (i.e., proportional to 1/voltage), so increasing that voltage reduces the wasted power.

(D) proportional to the square of the current, so reducing that current dramatically reduces the wasted power.

An optical fiber consists of a central core, a cladding layer around that core, and a wrapper around the cladding layer. What keeps light traveling inside the fiber?

(A) The light reflects from the aluminum wrapper and remains in the core and cladding layer.

(B) The light reflects from the aluminum cladding layer and remains in the core.

(D) The light experiences total internal reflection as it tries to move from the cladding layer to the wrapper.

You are taking a photograph of a child who is running toward the camera. As the child approaches the lens, what must the camera do in order to keep the child's image sharply focused on the image sensor?

(A) The camera must decrease the effective diameter of the lens.

(B) The camera must move the image sensor away from the lens.

(D) The camera must move the image sensor toward the lens.

You are standing on the shore of a small lake and you see the opposite shore reflected in the lake's calm surface. You are trying to photograph the fish swimming in the lake, but the reflection of the shore makes it hard to see the fish. To eliminate most of that reflection, you should put a filter in front of the camera's lens that blocks

(A) vertically polarized light.

(B) short wavelength light.

(D) long wavelength light.

You are standing near the wall in a darkened room and there is a window on the opposite wall. When you hold a magnifying glass (a converging lens) about 8 inches from the wall, a sharp image of the window frame appears on the wall. How does that lens form a sharp image of the window frame on the wall?

(A) The lens bends all the light rays from the entire window frame so that they converge to a single point on the wall.

(B) The lens bends the light rays from a single point on the window frame so that they converge to a window-frame-shaped spot on the wall.

(C) The lens converges all of the light rays from the window frame so that they all meet at a point half-way from the lens to the wall. Those rays continue on to form a sharp image on the wall.

(D) The lens bends the light rays from a single point on the window frame so that they converge to a single point on the wall.

When liquid glass is cooled to room temperature in a few minutes, what happens to the microscopic structure of that glass?

(A) Countless small crystals form throughout the glass.

(B) It doesn't change.

(D) The glass forms one nearly perfect crystal.

In a thermal fission nuclear reactor, a moderator slows the fission neutrons to thermal (slow) speeds. The reactor can then use natural or slightly enriched uranium, which are mostly uranium-238, because uranium-238

(A) absorbs slow neutrons.

(B) repels only fast neutrons.

(D) does not absorb slow neutrons.

As a drop of clear, colorless oil spreads out on the top surface of a puddle, you can see colored rings in the light reflected from the thin layer of oil. What is causing those colored rings?

(A) The clear oil is separating into its primary colors of light as it spreads outward on the water.

(B) The partial reflections from the oil layer's top and bottom surfaces are interfering with one another.

(C) Light is refracting at the surface of the oil and, because violet light travels faster in the oil than red light, the light separates into the colors of the rainbow.

(D) The clear oil is separating into its primary colors of pigment as it spreads outward on the water.

Two LEDs (light emitting diodes) are identical except that the conduction and valence levels of the LED #1 are separated by more energy than those of LED #2. Because of that difference, LED #1 emits

(A) dimmer light than LED #2.

(B) brighter light than LED #2.

(D) higher frequency light than LED #2.

A child is covered with positive charges and the hair on the top of her head is standing straight up. At the tip of one of these vertical hairs, in which direction is the electric field pointing?

(A) The electric field points straight down.

(B) The electric field points straight up.

(D) The electric field points horizontally forward.

One way for a jeweler to check if a gemstone is genuine is to immerse that gemstone in a clear, colorless liquid that has the same refractive index as the real gemstone. In other words, light travels at the same speed in the liquid as in the real gemstone. When the real gemstone is in that liquid,

(A) the gemstone exhibits total internal reflection from all of the surfaces on its far side (the side opposite the jeweler) and the back of the gemstone appears to be mirrored.

(B) the gemstone becomes opaque and no light is visible through it.

(D) the gemstone's surfaces become invisible and only the color of the gemstone (if any) can be seen.

The primary difference between red light from an LED (light emitting diode) and red light from a laser is that the red light from the LED is

(A) dimmer than the red light emitted by the laser.

(B) hotter than the red light emitted by the laser.

(D) many independent light waves and the red light from the laser is one large light wave.

Two billiard balls are rolling forward on a horizontal table, but the blue ball is traveling twice as fast as the yellow ball. The two balls roll off the edge of the table simultaneously. The yellow ball hits the ground

(A) after the blue ball.

(B) before the blue ball.

(D) at the same time as the blue ball, but the blue ball lands four times as far from the table as the yellow ball.

Two marbles roll off your porch simultaneously at the same speed, but one marble encounters a bump at the last minute so that it heads upward as it leaves the porch. The other marble heads forward horizontally as it leaves the porch. After leaving the porch,

(A) the two marbles reach the ground at the same moment but the marble that was heading forward travels farther from the porch than does the other marble.

(B) the marble that was heading forward reaches the ground before the marble that was heading upward.

(D) the two marbles reach the ground at the same moment and at the same distance from the porch.

Your curling iron was designed to operate on 120 volt alternating current, but you are traveling in Europe and your friend connects it to 230 volt alternating current. The curling iron quickly burns out because

(A) the correct amount of current flows through the curling iron's heating element, but that current alternates too rapidly and overheats the heating element.

(B) the voltage gradient in the curling iron's heating element is too large and too much current flows through the heating element.

(C) the temperature of 230 volt alternating current is much higher than the curling iron was designed to handle and it burns up the curling iron.

(D) the correct amount of current flows through the curling iron's heating element, but that current produces too many volts in the heating element and burns it up.

(A) Liquid glass is poured through a narrow slit so that it forms a ribbon of solid glass.

(B) Softened glass is stretched into sheets on a Teflon surface.

(D) Softened glass is rolled flat in ceramic rollers.

Unlike pure semiconductor, n-type semiconductor has some filled conduction levels and p-type semiconductor has some empty valence levels. Suppose you have two electrically neutral disks, one of n-type semiconductor and one of p-type semiconductor. When you touch the two disks, electrons migrate from the

(A) p-type semiconductor to the n-type semiconductor and the resulting electric field points from the p-type semiconductor toward the n-type semiconductor.

(B) n-type semiconductor to the p-type semiconductor and the resulting electric field points from the p-type semiconductor toward the n-type semiconductor.

(C) n-type semiconductor to the p-type semiconductor and the resulting electric field points from the n-type semiconductor toward the p-type semiconductor.

(D) p-type semiconductor to the n-type semiconductor and the resulting electric field points from the n-type semiconductor toward the p-type semiconductor.

A glass vase is almost perfectly clear. If you crush that vase into powder, it becomes white because

(A) light passing through it travels at the same speed, regardless of wavelength.

(B) oxygen in the air reacts with the newly exposed glass surface and turns that surface white.

(D) each surface in the crushed glass partially reflects light.

The Pauli exclusion principle observes that two indistinguishable electrons can never be in the same quantum wave. Suppose that Universe B did not obey that principle. How would the atoms there differ from the atoms in our universe?

(A) In Universe B, a typical atom would have only half as many electrons as a typical atom in our universe.

(B) In Universe B, a typical atom would have many possible orbitals, but all of its electrons would be in the lowest-energy orbital.

(D) In Universe B, a typical atom would have twice as many electrons as a typical atom in our universe.

When uranium fissions, its fragments include the nuclei of common elements such as iodine. These fission-produced iodine nuclei, however, tend to be radioactive because they often have

(A) too few neutrons.

(B) too many protons.

(D) too many neutrons.

You are visiting a planet orbiting a distant star. That star is identical to our sun and the planet is identical to earth except that its atmosphere is twice as thick as ours (it has more gas molecules). You look up at the sky when the star is directly overhead. Compared to the same situation on earth, the star looks

(A) slightly bluer than our sun and the sky is a dimmer blue than on earth.

(B) the same as our sun, but the sky is dimmer blue than on earth.

(D) the same as our sun, but the sky is brighter blue than on earth.

To sustain a nuclear chain reaction, an assembly of fissionable material must ensure that, on average, each nucleus that fissions

(A) produces at least two free nucleons (protons and neutrons).

(B) causes at least one subsequent fission.

(D) causes the release of at least one proton.

Two of your friends are pulling on opposite ends of a rope in the game of "tug of war." At this moment, your friend on the left is winning: both of them are moving to the left at constant velocity. The net force on the rope

(B) points toward the right.

(D) points straight down.

You are riding up a long escalator at a Washington DC metro station. You are traveling straight uphill at a steady pace, toward the exit of the escalator and the street outside. In which direction is the escalator pushing you?

(A) Directly uphill, toward the exit of the escalator.

(B) Directly forward (horizontally).

(D) Directly upward.

An iron wire is heated to 1000 degrees Celsius and is then allowed to cool to room temperature. The wire shrinks at first, then it suddenly gets longer, and then it continues to shrink. Why did the wire suddenly become longer?

(A) The iron abruptly stopped emitting thermal radiation and its temperature briefly rose at that transition.

(B) The iron's excess chemical potential energy suddenly became thermal energy and reheated it.

(D) The iron's crystal structure changed from austenite to ferrite.

Why is a radio station's antenna most effective at emitting the radio wave when its length is approximately 1/4 of the radio wave's wavelength?

(A) The antenna is then resonant at the radio station's frequency, making it easier for the station to move large amounts of charge up and down the antenna.

(B) The antenna needs to be long enough to accommodate the entire upward arrow of the radio wave's magnetic field.

(D) The antenna can then hold only a crest or a trough of the radio wave, ensuring that there is no destructive interference on the antenna.

Your hairdryer is on and it's blowing hot air. At this moment, one of the wires in its power cord is carrying current toward the hairdryer. That current is proportional to

(A) the net charge of that wire.

(B) one divided by the voltage difference between the two ends of the wire.

(D) one divided by the net charge of that wire.

How should you alter a camera’s converging lens to make a distant object appears larger in the photographs?

(A) Increase the diameter of the lens.

(B) Decrease the diameter of the lens.

(D) Decrease the curvature of the lens's two curved surfaces.

You leave a thick metal spoon with no sharp edges in your ceramic coffee mug as you reheat the coffee in the microwave oven. While the microwave oven is operating,

(A) the spoon is becoming radioactive, so that it is dangerous when you remove it from the oven.

(B) nothing happens to the spoon (apart from being heated by the coffee).

(D) the spoon carries a large alternating current.

You get on your bicycle and begin pedaling forward on level pavement. You travel forward faster and faster. As your speed is increasing in the forward direction, friction between the ground and the bicycle wheels is exerting

(A) a backward force on the bicycle.

(B) an upward force on the bicycle.

(D) zero force on the bicycle.

When you plug a toaster into a household electric outlet, the two metal blades of its plug connect with the two slots in the outlet. You start cooking toast and the outlet supplies 120-volt alternating current to the toaster. What is happening at those two connections?

(A) The voltage difference between the two connections reverses many times per second and the current flowing through each connection also reverses many times per second.

(B) At one moment, current flows through the left connection to the toaster and zero current flows through the right connection. A fraction of a second later, current flows through the right connection to the toaster and zero current flows through the left connection. This arrangement of current flow to the toaster alternates back and forth many times per second.

(C) The current flowing through each connection reverses many times per second, but the voltage difference between the two connections remains constant.

(D) The voltage difference between the two connections reverses many times per second, but the current flowing through each connection remains constant.

You accidently pinch the cord of your desk lamp in a drawer and cut through one of the two wires in the lamp's cord. Only one wire now connects the lamp to the electric socket. If you switch on the lamp,

(A) the normal amount of current will flow through both wires and the lamp will glow at its normal brightness.

(B) half the normal amount of current will flow through the one remaining wire and the lamp will glow at a quarter of its normal brightness.

(D) the normal amount of current will flow through the one remaining wire and the lamp will glow at half its normal brightness.

When a microwave is heating food in a microwave oven, the aspect of that microwave that is primarily responsible for heating the food is its

(A) electric charge.

(D) electric current.

An LED (light emitting diode) produces a photon (a single quantum wave of light) when an electron

(A) makes a radiative transition from the diode's n-type semiconductor to its p-type semiconductor.

(B) crosses from the diode's n-type semiconductor to its p-type semiconductor and then makes a radiative transition from a conduction level to an empty valence level.

(D) collides with an atom in the diode's gas discharge and causes that atom to emit an electromagnetic wave.

How does the molecular structure of solid glass compare to the structure of liquid glass?

(A) Solid glass has an orderly crystalline structure whereas liquid glass has a disordered structure.

(B) Both have similar disordered (non-crystalline) structures, but only the liquid glass can flow in response to stress or strain.

(C) Both have crystalline structures, but liquid glass's crystals are so tiny that they can move relative to one another and the glass can change its shape.

(D) Both have similar crystalline structures, but only the liquid glass can undergo slip in order to flow in response to stress.

You drop a bouncy ball on a cement sidewalk and the ball rebounds almost to its original height. During the bounce, the ball

(A) transfers almost zero momentum to the sidewalk, but it transfers a large amount of energy to the sidewalk.

(B) transfers a large amount of momentum to the sidewalk, but it transfers almost zero energy to the sidewalk.

(D) transfers a large amount of momentum to the sidewalk and it transfers a large amount of energy to the sidewalk.

A technician is building a transformer and he grabs the wrong spool of wire for the transformer's secondary coil. The wire he uses is only half as long as it should be, but has twice as much copper per foot. As a result, the secondary coil has half as many turns as expected, but has the correct weight. He plugs in the transformer and finds that the voltage rise in its secondary coil is

(A) twice what it is supposed to be.

(B) the same as it is supposed to be, but the current is twice what is expected.

(D) only half what it is supposed to be.

A moderator is a material that slows neutrons to thermal (slow) speeds. Both hydrogen atoms (in water) and carbon atoms (in graphite) have been used as moderators in thermal fission nuclear reactors. Of these two atoms, which is the most efficient at slowing fission neutrons (requires the fewest collisions) and why?

(A) Hydrogen is most efficient because its nucleus has almost the same mass as a neutron.

(B) Hydrogen is most efficient because it has one electron, just like a neutron.

(D) Carbon is most efficient because it has many electrons that can work together to drag a neutron to a stop.

On a bright day, the pupil of your eye (the circular opening through which you see) becomes very small in diameter. One consequence of having a tiny pupil is that

(A) distant and nearby objects do not appear relatively sharp at the same time. In other words, your depth of focus is small.

(B) the sizes of the real images projected on your retina are relatively small compared to when your pupil is wide open. In other words, you see a slightly reduced view of the world in front of you.

(C) the sizes of the real images projected on your retina are relatively large compared to when your pupil is wide open. In other words, you see a slightly enlarged view of the world in front of you.

(D) both distant and nearby objects appear relatively sharp at the same time. In other words, your depth of focus is large.