Physics 1060 - Spring 2015 - Final Exam - Posted Version

Problem 1:

Compared to a red LED (light-emitting diode), a blue LED

(A) contains a semiconductor with a smaller band gap (energy gap) between its valence band and its conduction band.

(B) operates at a higher temperature and therefore emits bluer light.

(D) contains a semiconductor with a larger band gap (energy gap) between its valence band and its conduction band.

Problem 2:

Your electric hairdryer was designed to operate on 120 volt alternating current. You are traveling in South Asia and your friend connects it to the local electric power, which is 240 volt alternating current. What happens to your electric hairdryer?

(A) The temperature of 240 volt alternating current is much higher than the hairdryer was designed to handle and it overheats.

(B) The correct amount of current flows through the electric hairdryer's heating element, but that current alternates too rapidly and overheats the heating element.

(C) The current in the hairdryer's heating element is about twice as large as it should be. The heating element consumes about 4 times as much power as it should and overheats.

(D) The hairdryer's heating element consumes the correct amount of electric power and operates normally.

Problem 3:

As a ball bounces on the floor, the floor exerts an upward support force on the ball. Can that upward support force on the ball be different in amount from the ball's weight?

(A) Yes. It can be greater than the ball's weight and it can be less than the ball's weight.

(B) Yes. It can be greater than the ball's weight. It cannot be less than the ball's weight.

(D) No. It can only be equal in amount to the ball's weight.

Problem 4:

Which of the following is experiencing a non-zero net force?

(A) An elevator operator traveling straight down at a constant speed in a tall elevator.

(B) A rock climber hanging motionless from a rock outcropping.

(D) A shopper moving at constant velocity while pushing a heavy grocery cart up a ramp.

Problem 5:

High-voltage power transmission wires are carrying electric power to a nearby city. Near each of those transmission wires, there is

(A) an electric field, but no magnetic field.

(B) neither an electric nor a magnetic field.

(D) an electric field and a magnetic field.

Problem 6:

Light travels at the same speed in salad oil as it does in cooking glass (Pyrex or Kimax). If a converging lens made from cooking glass is immersed in salad oil, the lens would produce

(A) strong reflections from its surfaces, but it would not refract light passing through it.

(B) no reflections from its surfaces, but it would strongly refract light passing through it.

(D) no reflections from its surfaces and it would not refract light passing through it.

Problem 7:

Which force is your weight? [The force that is your weight and not a force that is equal to your weight.]

(A) The force you exert on a trampoline as you land on that trampoline after jumping high above the trampoline's surface.

(B) The force you exert on a bathroom scale as you stand on that scale.

(D) The force that a bathroom scale exerts on you as you stand on that scale.

Problem 8:

Your heirloom porcelain teacup has beautiful gold decorations on it, including a gold ring that encircles the lip of the cup. If you heat the cup in a microwave oven, the gold ring will turn black in a few seconds because the microwaves will

(A) magnetize the gold ring and cause it to attract black iron particles in the paint.

(B) shift electrons between orbitals in the gold atoms and cause the gold atoms to emit black light.

(D) interfere destructively inside the gold ring and shift its color from gold to black.

Problem 9:

What is it about water that makes it easy to heat in a microwave oven?

(A) Water molecules are positively charged.

(B) Water is a good conductor of electricity.

(D) Water is an electrical insulator.

Problem 10:

The glass tube of a fluorescent lamp contains mercury vapor. An electric discharge in that low-density vapor produces light. How does the white powder on the inside of the glass tube affect the light emitted by the fluorescent lamp?

(A) The powder amplifies white light from the mercury discharge, making it brighter and more energy efficient.

(B) The powder is a phosphor that converts ultraviolet photons from the mercury discharge to visible photons.

(D) The powder scatters white light from the mercury discharge in all directions, hiding the dazzlingly bright line of discharge from view.

Problem 11:

How should a camera's converging lens be changed in order to project larger images on its image sensor and thereby provide enlarged views of distant objects?

(A) Reduce the curvature of the lens

(B) Reduce the diameter of the lens

(D) Increase the diameter of the lens

Problem 12:

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

(A) before the blue ball.

(B) after the blue ball.

(D) at the same time as the blue ball, but the green ball lands half as far from the table as the blue ball.

Problem 13:

A bowling ball is rolling at constant velocity from one end of a horizontal bowling lane to the other end. What horizontal force is the lane exerting on the bowling ball (neglect any effects due to the air)?

(A) The lane exerts a steady forward force on the ball to keep it moving forward.

(B) The lane exerts a forward force on the ball and that force decreases steadily as the ball moves forward along the bowling lane.

(D) The lane exerts zero horizontal force on the ball.

Problem 14:

During use, the number of electrons in the main passage or "channel" of an MOSFET can be altered by changing the

(A) size of each electron.

(B) electric charge of each electron.

(D) electric charge on the MOSFET's gate.

Problem 15:

With your camera focused on a nearby statue, the mountains behind the statue appear fuzzy in the photographs. Which two changes would sharpen the appearance of those mountains in the photographs?

(A) Moving the camera lens father from the image sensor or increasing the effective diameter of the camera lens.

(B) Moving the camera lens closer to the image sensor or reducing the effective diameter of the camera lens.

(D) Moving the camera lens farther from the image sensor or reducing the effective diameter of the camera lens.

Problem 16:

An MOSFET can conduct electric current only when its main passage or "channel" has

(A) a net positive electric charge.

(B) no electrons in its conduction levels (and no empty valence levels).

(D) a net negative electric charge.

Problem 17:

A negatively charged storm cloud is passing overhead as you step into your car in the middle of an open field. For the brief moment while you are touch both the ground and the car, electric charge can move between the ground and car. When you are completely inside the car and the car's tires insulate it from the ground, what is the car's electric charge?

(A) The car's charge cannot be determined without measuring it.

(B) The car is positively charged.

(D) The car is electrically neutral.

Problem 18:

Light can travel from one city to another through a glass optical fiber. How does the fiber guide the light so well for such a long distance?

(A) The surface of the fiber has an electric charge that confines the light to the center of the fiber.

(B) The surface of the fiber has a magnetic field that confines the light to the center of the fiber.

(D) The light experiences total internal reflection each time it encounters the surface of the fiber's glass core.

Problem 19:

You're at the lake and watch two children of the same size jump off a dock simultaneously. They both rise to the same peak height after the jump, but the boy jumped upward and forward (at an angle away from the dock) while the girl jumped upward. After they leave the dock,

(A) girl reaches the water before the boy.

(B) boy reaches the water before the girl.

(D) the two children reach the water at the same moment, but the boy travels farther from the dock than does the girl.

Problem 20:

A special transformer has two secondary coils that share the same environment and each coil provides electric power to its own circuit. One secondary coil has 100 turns (it circles the transformer's iron core 100 times), while the other secondary coil has 200 turns. When the transformer is in operation and the two secondary coils are providing power to their separate circuits, what is definitely true about the two secondary coils?

(A) The 200-turn secondary coil is carrying twice the current of the 100-turn secondary coil.

(B) The 200-turn secondary coil is providing twice the voltage rise of the 100-turn secondary coil.

(D) The 200-turn secondary coil is providing half the voltage rise of the 100-turn secondary coil.

Problem 21:

When p-type semiconductor and n-type semiconductor touch, they form a pn-junction. A few electrons spontaneously migrate from conduction levels in the n-type side to valence levels in the p-type side. The pn-junction then acts as a one-way device for electric current. For current to flow through the pn-junction, electrons must approach the junction in the

(A) valence levels of the p-type semiconductor and leave the junction in the conduction levels of the n-type semiconductor.

(B) valence levels of the n-type semiconductor and leave the junction in the conduction levels of the p-type semiconductor.

(C) conduction levels of the n-type semiconductor and leave the junction in the valence levels of the p-type semiconductor.

(D) conduction levels of the p-type semiconductor and leave the junction in the valence levels of the n-type semiconductor.

Problem 22:

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) long wavelength light.

(B) vertically polarized light.

(D) horizontally polarized light.

Problem 23:

Separating uranium-235 from uranium-238 is extremely difficult because

(A) uranium-235 is unstable and falls apart during the separation process.

(B) uranium-235 and uranium-238 both have the same number of neutrons.

(D) uranium-235 and uranium-238 are chemically indistinguishable.

Problem 24:

A low-pressure sodium vapor lamp produces monochromatic yellow light, light with only one frequency and therefore only one color. In a high-pressure sodium vapor lamp, that yellow light is spread out across a wide range of frequencies. What aspect of the high-pressure environment causes its sodium atoms to emit that wider range of frequencies?

(A) High pressure squeezes the yellow light and changes both its wavelength and its frequency. Since the lamp's pressure varies from place to place, its yellow light has wide range of frequencies.

(B) Collisions are common at high pressures. If a sodium atom is hit while emitting a photon of yellow light, the collision energy can alter the energy of the photon and thus change its frequency.

(C) The atomic structure of a sodium atom changes with pressure. At high pressure, the sodium atom begins to resemble the neon atom and that mixed character leads to a wider range of frequencies of light.

(D) The number of electrons in a sodium atom changes with pressure. At high pressure, the sodium atom has more electrons and therefore emits light with a wider range of frequencies.

Problem 25:

A solid metal sphere has a net positive charge and everything is at equilibrium and motionless. The electric field inside the sphere

(A) points toward the center of the sphere and the electric field outside the sphere points away from the sphere.

(B) is zero and the electric field outside the sphere points away from the sphere.

(D) points away from the center of the sphere and the electric field outside the sphere points away from the sphere.

Problem 26:

An alpine skier is participating in a downhill race. The slope of the downhill race course is like a steep ramp, except for several dips (depressions or low spots) at which the skier is briefly off the ground (loses contact with the ground). What net force does the skier experience? (Neglect friction and effects due to the air.)

(A) While on the ground, the net force points forward horizontally. While off the ground, the net force points downhill.

(B) While on or off the ground, the net force points downhill.

(D) While on the ground, the net force points downhill. While off the ground, the net force points downward.

Problem 27:

The metal walls of microwave oven's cooking chamber are good conductors of electricity. If those walls were poor conductors electricity, they would

(A) become positively charged when the oven is on.

(B) become hot when the oven is on.

(D) emit sparks when the oven is on.

Problem 28:

If you carry a portion of positive charge from a region of high voltage to a region of low voltage, that charge will

(A) become a smaller positive charge as a result of that move.

(B) do work on you during that move.

(D) do negative work on you during that move.

Problem 29:

Glass is transparent, so why does powdered glass appear white?

(A) Partial reflections from its countless surfaces scatter light in all directions and give the powder its white appearance.

(B) Glass surfaces oxidize when exposed to air and turn white. Powdering glass causes that oxidation.

(D) Powdering glass turns it back into sand and each surface of a sand grain is white.

Problem 30:

An electrical insulator cannot conduct electric current because

(A) its bands of levels are either full or empty, so its electrons cannot shift between levels.

(B) it is electrically neutral and experiences no force when exposed to an electric field.

(D) it is electrically charged and experiences a force when exposed to an electric field.

Problem 31:

Running on soft dry sand is exhausting, so you switch to running on hard wet sand. The hard wet sand takes less energy from you because

(A) it doesn't move downward as you push downward on it, so you do almost zero work on it.

(B) its water content gives it more mass and that prevents it from absorbing energy.

(D) it stops the downward motion of your foot faster and thus absorbs less of your momentum.

Problem 32:

Which of the following is a digital representation of information?

(A) A phonograph record (a spiral groove cut in a plastic disk), used to reproduce sound in a phonograph.

(B) An FM radio broadcast, used to convey sound information from a radio station to a radio receiver.

(D) An AM radio broadcast, used to convey sound information from a radio station to a radio receiver.

Problem 33:

Two sheets of plastic form a stack on a glass table. The bottom sheet has a large negative charge and the top sheet has a large positive charge. The charge on each sheet remains unchanged as you lift the top sheet upward, but the voltage of the top sheet

(A) increases and the voltage of the bottom sheet decreases.

(B) decreases and the voltage of the bottom sheet increases.

(D) increases and the voltage of the bottom sheet increases.

Problem 34:

The nuclear chain reactions that shatter uranium and plutonium nuclei during nuclear explosions involve projectiles (moving objects). Those projectiles emerge from shattered nuclei and cause other nuclei to shatter. What are those projectiles?

(A) Protons

(B) Neutrons

(D) Electrons

Problem 35:

An atom is often drawn as a spherical nucleus with several spherical electrons orbiting around it:

. Such drawings fundamentally misrepresent atomic structure because, in a real atom, electrons

(A) orbit the nucleus in endless spirals, not closed loops.

(B) are much smaller spheres than the nucleus.

(D) all orbit the nucleus horizontally and circle the nucleus's equator.

Problem 36:

When you accumulate a large static electric charge and move your finger toward a metal pipe, a dramatic spark leaps between your finger and the pipe. If you hold a sharp pin in your hand and move the point of the pin toward the pipe, there will be

(A) little or no spark.

(B) a much brighter spark, but the length of that spark will be the same as before.

(D) a spark just as before.

Problem 37:

Electric power is transmitted long distances as a relatively small current at a relatively high voltage. Why is that arrangement used?

(A) Increase the voltage differences between the wires reduces the power wasted by those wires. Decreasing the current in those wires allows those large voltages to transmit large amounts of power.

(B) Increasing the voltage difference between the wires reduces the resistance of those wires and causes their currents to decrease.

(D) Decreasing the current in each wire reduces the power those wires consume. Increasing the voltage difference between the wires allows those small currents to transmit large amounts of power.

Problem 38:

When properly wired, an electrical outlet in the United States has two slots, Power and Neutral, along with a round opening, Ground. The voltage of Power (the short slot) fluctuates between +170 volts and -170 volts, but the voltage of Neutral (the long slot) remains at or very near 0 volts. Ground is connected by wire directly to Earth and Earth's voltage is 0 volts. A daredevil is standing barefoot in water on the ground. When he sticks a metal paper clip in those three openings, one at time, he receives

(A) a serious shock from the Power slot, but no significant shock from the other two openings.

(B) a serious shock from both the Power and Neutral slots, but no significant shock from the Ground opening.

(D) a serious shock from all three openings.

Problem 39:

Since energy is a conserved quantity, the energy released when a uranium or plutonium weapon explodes was stored as potential energy in the uranium or plutonium prior to the explosion. Which force is associated with that potential energy? [Definition: nucleons include both protons and neutrons]

(A) The nuclear force between nucleons

(B) The strong force within nucleons

(D) The gravitational force between nucleons

Problem 40:

What force does a stationary north magnetic pole exert on a stationary positive electric charge?

(A) The north magnetic pole attracts the positive electric charge.

(B) The north magnetic pole exerts a Star Wars force on the positive electric charge.

(D) The north magnetic pole repels the positive electric charge.

Problem 41:

Light from a laser pointer can exhibit dramatic interference effects. Radiation from which other source can exhibit similarly dramatic interference effects?

(A) Light from the sun

(B) The microwave from a microwave oven's antenna

(D) Light from an LED (light-emitting diode)

Problem 42:

Optical microscopes provide greatly enlarged views of tiny objects. They have a limit, however, because they cannot resolve objects or features that are much smaller than

(A) the wavelength of visible light.

(B) the thickness of the microscope's lenses.

(D) the diameter of the microscope's lenses.

Problem 43:

Following a nuclear explosion, the shattered fragments of uranium nuclei attract electrons and become seemingly normal atoms, such as iodine atoms. Compared to a naturally occurring iodine atom, a uranium-fragment iodine atom has too many

(A) ions and is therefore electrically charged.

(B) electrons and is therefore toxic.

(D) protons and is therefore radioactive.

Problem 44:

While a light wave from a distant star is traveling through empty space on its way to the earth, that light wave consists of

(A) an electric field and a magnetic pole.

(B) an electric charge and a magnetic pole.

(D) an electric charge and a magnetic field.

Problem 45:

The needle of a magnetic compass is held motionless in a uniform (the same everywhere) magnetic field that points upward. With the needle oriented horizontally, so that its north end points to the right and its south end points to the left, what magnetic influences does the needle experience?

(A) The needle experiences a clockwise magnetic torque and a downward magnetic force.

(B) The needle experiences a counterclockwise magnetic torque and an upward magnetic force.

(D) The needle experiences zero magnetic torque and zero magnetic force.

Problem 46:

On a day when the atmosphere overhead has relatively few tiny particles in it, which of the follow do you see?

(A) The sky appears relatively dark and its color is blue-violet. At sunrise and sunset, the sun's color shifts to rich orange or even red.

(B) The sky appears relatively bright and its color is whitish-blue. At sunrise and sunset, the sun's color remains relatively white or yellow.

(C) The sky appears relatively dark and its color is blue-violet. At sunrise and sunset, the sun's color remains relatively white or yellow.

(D) The sky appears relatively bright and its color is whitish-blue. At sunrise and sunset, the sun's color shifts to rich orange or even red.

Problem 47:

You are standing in a vast open field, facing the vertical transmitting antenna of an AM radio station miles away. From your perspective, what are the directions of the radio wave's electric and magnetic fields?

(A) The electric field points alternately left and right. The magnetic field points alternately up and down.

(B) The electric field points alternately up and down. The magnetic field points alternately left and right.

(C) The electric field points alternately up and down. The magnetic field points alternately toward and away from the transmitting antenna.

(D) The electric field points alternately left and right. The magnetic field points alternately toward and away from the transmitting antenna.

Problem 48:

Which physics concept associated with light does a camera lens use to project a real image onto the camera's image sensor?

(A) Refraction

(B) Reflection

(D) Interference

Problem 49:

A person who is "farsighted" sees distant objects clearly but can't focus on the text in a nearby book. That text appears blurry because each eye's lens forms its real image beyond the retina. To move the real image of the text toward the lens so that it forms on the retina, the person should wear glasses that contain

(A) diverging lenses with short-focal lengths.

(B) diverging lenses with low f-numbers.

(D) diverging lenses with long-focal lengths.

Problem 50:

Violet light travels slightly slower than red light as they pass through water. If the opposite were true, how would that change the appearance of a rainbow?

(A) The rainbow's arc would be inverted (U-shaped) and the order of its colors would be reversed (red on the inside).

(B) The rainbow would remain arc-shaped, but the order of its colors would be reversed.

(C) The rainbow's arc would be inverted (U-shaped), but the order of its colors would remain unchanged (blue on the inside).

(D) The rainbow would remain arc-shaped and the order of its colors would remain unchanged.

Problem 51:

You have two identical electric space heaters, both of which are plugged into the same electrical outlet of your home. It's a cold winter day and you turn on one of the heaters. A current of 10 amperes flows through the wires of your home (to provide power to the heater) and wastes 1 watt in those wires. When you turn on the second heater, a current of

(A) 10 amperes flows through the wires of your home and wastes 2 watts in those wires.

(B) 40 amperes flows through the wires of your home and wastes 2 watts in those wires.

(D) 20 amperes flows through the wires of your home and wastes 4 watts in those wires.

Problem 52:

A flashlight with one battery and one LED lamp is turned on and produces light. Which point in the flashlight's circuit has the greatest (positive) voltage?

(A) The point at which current enters the LED lamp.

(B) The point at which current leaves the battery.

(D) The point at which current enters the battery.

Problem 53:

The radio wave of your favorite FM station has a wavelength of 3 meters. You decide to install a straight wire antenna on the metal hood of your new car. You start with a very short antenna and find that increasing its length improves its reception until it reaches 0.75 meters long. Antennas longer than 0.75 meters don't improve the reception. What is special about using a 0.75 meter antenna with a 3-meter radio wave?

(A) When an antenna above a metal surface is a quarter wavelength long, the radio wave causes charge to move resonantly on that antenna.

(B) The metal hood absorbs three quarters of the radio wave (left, right, and down), leaving just one quarter of the wave for the antenna. The remaining portion matches a quarter wavelength antenna.

(C) With the metal hood beneath it, the radio wave can move only upward and it travels only a quarter of its wavelength from the base of the antenna.

(D) The radio wave's electric field is a quarter of its wavelength long, so it fits perfectly in a quarter wavelength antenna.

Problem 54:

You walk to class at a steady pace along a flat, horizontal path. Your backpack weighs 20 newtons and your trip is 100 meters long. How much work do you do on your backpack?

(A) 1/5 joule (1/5 newton-meters).

(B) 0 joules (0 newton-meters).

(D) 5 joules (5 newton-meters).

Problem 55:

To win a stuffed animal at the fair, you must knock a brick off a shelf by throwing bouncy balls and beanbags at it. The balls and beanbags have identical masses and you throw them at equal velocities. A bouncy ball hits and rebounds toward you, while a beanbag hits and stops. Compare the momentum each object transfers to the brick.

(A) The bouncy ball transfers more forward momentum to the brick than does the beanbag.

(B) The two objects transfer the same momentum to the brick, even if the brick doesn't move.

(D) The two objects transfer the same momentum to the brick, but only if the brick moves. If the brick doesn't move, they transfer zero momentum to it.

Problem 56:

In the United States, the licensed radio wave frequencies of two different AM radio stations in the same city are always separated by at least 10,000 cycles per second (10 kilohertz). Why can't two stations use radio wave frequencies separated by only 1 cycle per second (1 hertz)?

(A) Radio waves that are too close in frequency will exert electrostatic forces on one another.

(B) Tuning a radio receiver to just one of such closely spaced radio wave frequencies would be essentially impossible.

(C) Once a radio wave carries sound information, it includes a range of frequencies near its official frequency. The two stations' actual frequencies would therefore overlap.

(D) Radio waves that are too close in frequency will exert magnetostatic forces on one another.

Problem 57:

During a particular brown out, the voltage of the electrical power provided to your home by the power company is reduced by 5%. The voltage drop across your reading lamp is reduced by 5% so the current passing through it is also reduced by 5%. Overall, the power consumed by the lamp

(A) drops by about 10%.

(B) drops by about 25%.

(D) drops by about 5%.

Problem 58:

You are miles away from a radio station, yet its radio wave affects your car's antenna. The electric field at your car's antenna is being produced by the radio wave's

(A) changing magnetic field.

(B) negative electric charge.

(D) positive and negative electric charges.

Problem 59:

A drop of clear oil spreads out on the surface of calm water. When illuminated by sunlight, that oil film appears colored. What causes its colored appearance?

(A) The clear oil becomes colored when it interacts with water and begins to absorb certain wavelengths of light.

(B) The clear water becomes colored when it interacts with oil and begins to absorb certain wavelengths of light.

(C) You are observing interference effects between the partial reflections from the top and bottom surfaces of the oil film.

(D) The interface between oil and water can only reflect certain colors of light.

Problem 60:

A metal ball has a negative charge. The voltage of the metal ball is

(A) greater than zero.

(B) zero because voltage requires both negative and positive charges.

(D) zero because voltage is a characteristic of positive charge.