Physic 3
In an isochoric process, no work is done. Which of the below statements correctly explain why no work is done in an isochoric process?
Because the volume does not change in an isochoric process, there is no displacement, therefore no work.
Which has the higher frequency, red light or blue light?
Blue
Which of the following INCORRECTLY compares (i.e. point out commonalities) electricity and magnetism?
Both electric and magnetic fields produce forces on their mutual charges—magnetic field pushes/pulls electric charges and vice versa.
Which of the following correctly compares (i.e. point out commonalities) electricity and magnetism?
Both electricity and magnetism produce forces that act at a distance, whose magnitude decreases with increasing distance.
Each of the statement below describes a property of one of the methods of heat transfer. Match them to the method of heat transfer which the statement describes. A. conduction B. convection C. radiation
- A direct line-of-sight is needed for this mechanism of heat transfer. (C) - There is no movement of material for this mechanism of heat transfer, and the heat transfer can take place through vacuum. (C) - Material moves along with heat in this mechanism of heat transfer. (B) - When we say "heat rises", we are referring to this mechanism of heat transfer. (B) - Presence of material is necessary for this mechanism of heat transfer, but there is no movement of the material. (A)
The Kelvin temperature scale is special in that it is the only absolute temperature scale in use. By "absolute temperature scale," we mean that the zero point of the Kelvin scale has a significant physical meaning. Compare this against the zero point of the Celsius scale, which is the melting point of ice—but why should ice (or water) have such a special role in defining the zero point? It is for this reason both the Celsius scale and the Fahrenheit scale are relative temperature scales. Choose all statements below which correctly state the physical meaning(s) of the zero point of the Kelvin scale, 0 K.
- At the zero point of the Kelvin scale (0 K), a hypothetical gas that remained in gas phase has zero pressure and zero volume. - The zero point of the Kelvin scale (0 K) is where all microscopic thermal motions come to a stop.
Although they are distinct processes, heat transfer and work done can produce similar effects, as demonstrated in Joule's experiment. Choose all statements below which correctly compare and contrast heat transfer with work done.
- Both heat transfer and work move energy from one object to another. - Heat transfer does not result in macroscopic displacement of objects, while work results in a displacement. - Heat transfer occurs spontaneously from a hot object to a cold object in thermal contact, but additional specifications are needed to know whether work will be done.
Consider following statements, each of which describes a law of physics in English. Choose the four statements which represent the four Maxwell's equations describing electromagnetism.
- Electric field lines start on positive charges and end on negative charges. - Magnetic field lines are continuous, having no beginning or end. - Magnetic fields are generated by currents or by changing electric fields. - A changing magnetic field induces an electric field
Ferromagnets, or "permanent magnets", are most common ways we encounter magnetism in everyday circumstances. Choose the statements below which correctly describe how ferromagnets work.
- Ferromagnets are made of materials which form magnetic domains, macroscopic regions where the magnetic poles of individual atoms are aligned. - Hard blows or heating the ferromagnets may demagnetize them, reducing their ability to produce magnetic fields. - Ferromagnets can be produced by hard blows or heating certain materials in a strong magnetic field.
Choose the statements below which correctly defines or describes heat capacity.
- Heat capacity of an object increases with the amount of material present in the object. - Heat capacity refers to amount of heat transfer necessary to change the temperature of the object by some amount.
You have seen several statements of Second Law of Thermodynamics in the textbook. Among the statements below, choose all that are statements of Second Law of Thermodynamics.
- Heat spontaneously flows from hot to cold. - A heat engine cannot convert all heat input into work. - The most disordered state is the most likely state to occur. - A reversible Carnot engine has the greatest possible efficiency of any heat engine operating between two temperatures. - The total entropy of an isolated system never decreases.
Choose all correct descriptions and statements of First Law of Thermodynamics below.
- If there is no heat input, work done by the system decreases its internal energy. - The First Law of Thermodynamics says that the total energy, including heat energy, is conserved. -If there is no change in the internal energy, then net heat input is equal to the work done by the system.
Choose all statements below which correctly describe expected features of correctly drawn magnetic field lines.
- The field lines begin on north poles and end on south poles. - The field lines must never cross each other.
Choose all physical objects below which produces magnetic fields.
- a single electron - an electric current - a moving electric charge - a magnetized iron bar - a single atom
Match below named thermodynamic processes with the correct description. adiabatic sobaric isothermal isochoric
- adiabatic (process in which no heat transfer takes place) - sobaric (process taking place under a constant pressure) - isothermal (process taking place with a constant temperature) -isochoric (process taking place with a constant volume)
A given substance can change among the three common phases of matter (solid, liquid, and gas) with the addition or removal of heat. For each of the process listed below, correctly match it with whether the processes requires heat (cooling process) or if it releases heat (heating process). A. requires heat (cooling process) B. releases heat (heating process)
- freezing (liquid to solid) (B) - vaporization (liquid to gas) (A) - melting (solid to liquid) (A) - condensation (gas to liquid) (B)
As a block of ice is heated, it first heats up, and then at 0°C, it begins to melt, with the temperature staying constant at 0°C until all the ice melts. Then as the resulting water is continued to be heated, its temperature goes up, and then an 100°C, it begins to boil, with the temperature staying constant at 100°C until all the water turns into steam. The figure below illustrates this process. Rank the processes listed below in the order of amount of heat energy it takes to occur, from the largest to smallest. A. takes the most heat energy B. takes the second most heat energy C. takes the third most heat energy D. takes the least heat energy
- heating up ice at -20°C to 0°C (D) - vaporization of water into steam (A) - melting of ice into water (C) - heating up water from 0°C to 100°C (B)
what direction is the force that acts on a current-carrying wire placed in a magnetic field?
- perpendicular in direction to the magnetic field
Electrical current is measured in units of "ampere", or "coulombs per second" (1A=1C/s). When you measure 1 ampere of current, what are you actually measuring?
1 ampere of current is measuring 1 coulomb of charge crossing a pre-defined boundary every second.Incorrect
Household electric power is usually billed in units of cents per kilowatt-hour. How many joules is one kilowatt-hour?
1 kilowatt-hour = 3,600,000 joules
Consider a 1-dimensional arrangement of three charges. Two charges are already placed as shown below. In which of the three regions could a third charge be placed and the net electric force on the third charge will be zero?
A
Which of the following below INCORRECTLY describes or defines an "electric field"?
All charges placed within an electric field are pushed in the direction of the electric field.
In what way are magnetic poles very different from electric charges?
All magnets have both north and south poles. Electric charges (positive and negative) can exist as singular entities.
Which of the following is NOT an acceptable statement of the Second Law of Thermodynamics?
All statements above are acceptable statements of the Second Law of Thermodynamics.
Choose the statement below which most correctly describes one of the named thermodynamic processes.
An adiabatic process is a process in which no heat transfer takes place.
Which statement below best describes the interaction between an electric charge and magnetic fields?
An electric charge only feels a force from the magnetic field when it is moving.
What produces an electromagnetic wave?
An oscillating or accelerating electric charge
An electric motor can consist of a current loop in a magnetic field, as shown in below figure.
As current flows through the loop, the magnetic field exerts a force perpendicular to the wire, which generates a torque on the loop, causing the loop to rotate.
An electric motor can consist of a current loop in a magnetic field, as shown in below figure. Choose the statement below which most correctly describes how an electric motor works.
As current flows through the loop, the magnetic field exerts a force perpendicular to the wire, which generates a torque on the loop, causing the loop to rotate.
Choose the statement below which correctly states the physical meaning of the zero point of the Kelvin scale, 0 K.
At the zero point of the Kelvin scale (0 K), a hypothetical gas that remained in gas phase has zero pressure and zero volume.
Heat pump is a device which uses work input to push heat from low-temperature reservoir into high-temperature reservoir (the opposite of the spontaneous direction of heat flow). Which of the following expressions gives the correct coefficient of performance (a measure of efficiency) for a heat pump? Standard symbols are in use (W for work, QH for heat exchange with high-temperature reservoir, and QC for heat exchange with low-temperature reservoir).
COP=QH/W
You are an operator of colored spotlights for a live event. When you shine the red spotlight and the green spotlight on the feature presenter, with the beams of spotlight overlapping on the presenter, what color of spotlight is seen through the mixture of the two colors?
Color yellow is seen for the mixture of red and green spotlight.
A construction very similar to a motor (see figure below) can be used as a generator. By turning the loop of wire, a current can be generated, which can be used to power many things. Choose the statement below which most correctly explains this phenomenon.
Current is generated as a result of induced voltage according to Faraday's Law, which says that as magnetic flux through the loop changes, a voltage is induced around the loop.
Consider following statements, each of which describes a law of physics in English. Which of the following does NOT represent one of the four Maxwell's equations describing electromagnetism?
Electrostatic force is a conservative force.
Ferromagnets, or "permanent magnets", are most common ways we encounter magnetism in everyday circumstances. Choose the statements below which correctly describes how ferromagnets work.
Ferromagnets can be produced by hard blows or heating certain materials in a strong magnetic field.
An imaging system, such as a system of lenses or mirrors, may form a real image or a virtual image. Which of the following statements most correctly describe a virtual image formed by an imaging system?
For a virtual image, the light rays only appear to come from the location of the image but they do not come to a sharp focus at that location.
Choose the statement below which most correctly compares and contrasts heat pump with a refrigerator.
Heat pump uses input work to pump heat into the high-temperature reservoir; refrigerator uses input work to remove heat from the low-temperature reservoir.
Latent heat refers to the heat transfer necessary to achieve phase change (net heat input for changing solid into liquid, or changing liquid into gas) while temperature of the material remains the same (hence "latent"). Choose the statement below which correctly states why this heat transfer is necessary (for example, for solid-to-liquid phase change).
Heat transfer is necessary because pulling molecules apart from each other to break the bonds in solids takes energy (increases potential energy), even though the molecules won't be moving any faster.
Choose the statement below which INCORRECTLY compares and/or contrasts "heat transfer" with "work done."
Heat transferred raises temperature of the object, while the work done cannot raise temperature of the object.
In an isothermal process, the temperature of the gas remains the same. However, despite the constant temperature, in general, the net heat input in an isothermal process is not zero. Which of the statements below correctly explains why?
If work is done by the gas—for example, in an expansion—in order to keep the temperature the same, net heat input is necessary to conserve energy.
Choose the statement below which correctly states the melting point of ice and boiling point of water (in that order) in one of the three common temperature scales.
In the Fahrenheit scale the melting point of ice and boiling point of water are 32 and 212.
Electrostatic force, like the gravitational force, is an "inverse square law." Choose the most correct description of an inverse square law below.
Inverse square law describes a force whose magnitude decreases with increasing distance, so that at double the distance, force is one-fourth the original magnitude.
Which rule below correctly describes the attraction and repulsion of magnets?
Like poles repel each other while opposite poles attract.
A given substance can change among the three common phases of matter with the addition or removal of heat. Choose the statement below which correctly states whether the given process requires heat (cooling process) or releases heat (heating process).
Melting (solid to liquid) requires heat (cooling process).
A 60-watt lightbulb operates on household line voltage of 110 volts and, while it is on, has an effective resistance of 202 Ω. Calculate the amount of current flowing through the 60-watt lightbulb while it is on.
The amount of current is 0.55 A.
In the San Francisco Bay Area, you experience effects of microclimate, where climate experienced in one area (Alameda and Oakland for example, to the immediate east of the bay) is substantially different from climate experience in another area no more than 10 miles away (Orinda for example, located to the east of Oakland, across a mountain range). On a hot day, the temperature in Orinda can be 10°F or more higher than the temperature in Oakland. Which of the statements below correctly explain what causes this difference in climate between Oakland and Orinda?
Oakland is situated near a large body of water, and due to its large heat capacity, temperature of body of water rises more slowly than land.
Choose the statement below which correctly compares and/or contrasts different temperature scales commonly in use in the world.
One degree difference in °C represents the same temperature change as difference of 1 K.
Voltage (or electric potential) is closely related to other important physical quantities. Choose the correct relationship involving voltage (V) below; all symbols used with their standard meanings in mechanics and electrostatics.
PE=qV
Light is a transverse wave and can be polarized. A polarizing filter can be used to create a polarized light from unpolarized light, as illustrated in the figure below. What physical quantity does the polarization of light represent?
Polarization of light represents the orientation of electric field in the light.
Which of the following correctly states Ohm's Law? Standard symbols are in use: V is voltage, I is current, R is resistance, etc.
R=V/I
An electric stovetop may use anywhere from 1000 W to 3000 W while it is on. Estimate how much current an electric stovetop of power rating 2000 W draws while it is on. Assume household line voltage of 110 volts.
The 2000-W stovetop draws a current of 18.2 A while it is on.
Typical power rating of a microwave is about 1000 watt. Estimate how much current a microwave of power rating 700 watt draws while it is on. Assume household line voltage of 110 volts.
The 700-W microwave draws a current of 6.4 A while it is on.
Carnot efficiency is a useful tool to quickly estimate possible efficiency for different situations. A lecture-demonstration Stirling engine runs on heat from a hot cup of coffee at 350 K; assume the applicable low-temperature thermal reservoir is at the approximate room temperature 300 K. Estimate the Carnot efficiency.
The Carnot efficiency is 14%.
Which statement below best describes what happens when an electron is released from rest near the north pole of a bar magnet?
The electron feels no force due to the magnet
Which statement below best describes what happens when an electron is released from rest near the north pole of a bar magnet?
The electron feels no force due to the magnet.
Choose the statement below which correctly describes an expected feature of correctly drawn magnetic field lines.
The field lines begin on north poles and end on south poles.
What must change in order for electromagnetic induction to occur in a wire coil?
The magnetic field through the coil must change.
Navigators since ancient times have used compass—a small, magnetized piece of material set in a way to rotate easily—for navigation. Our name for "north" magnetic pole comes from the end of the compass that points north and "south" magnetic pole comes from the end of the compass that points south. Which of the below statements most correctly explain why the compass needle orients itself this way?
The north pole of the compass is attracted to the south magnetic pole of Earth, which is located near the geographic north pole.
Using the ideal gas law, PV=NkT, where � is the Boltzmann constant (�=1.381×10-23J/K), find the number of gas molecules in an ideal gas at 80 kPa (compare: atmospheric pressure is 101.3 kPa) in a volume of 1 m3 (compare: a volume of 1 m3 is what most adults can comfortably crawl into), at a temperature of 298 K (ice melts at 273 K; the "room temperature" is 293 K).
The number of gas molecules is 1.94 ×1025molecules in the given volume.
It is common in adiabatic expansions for the temperature of the gas to decrease. Which of the following explains the reason why best?
The temperature decreases in an adiabatic expansion because the gas does work and this energy is expended from internal energy.
Which of the following is NOT a statement of the Second Law of Thermodynamics?
The total entropy of an isolated system never increases.
How is the wavelength of light related to its frequency?
The wavelength is inversely proportional to the frequency.
AM (amplitude-modulated) radio stations use carrier waves of frequency approximately around 1 MHz. FM (frequency-modulated) radio stations use carrier waves of frequency approximately around 100 MHz. Which statement below is most correct?
The wavelength of AM radio stations is about 100 times greater than the wavelength of FM radio stations.
A given substance can change among the three common phases of matter with the addition or removal of heat. Choose the statement below which correctly states whether the given process requires heat (cooling process) or releases heat (heating process).
Vaporization (liquid to gas) requires heat (cooling process).
Consider a glass pane that is separating two medium that may be different (e.g. air and water) or not (e.g. air and air). When is the angle at which a ray of light strikes the glass pane on one side NOT the same as the angle at which it exits the glass pane on the other side?
When it enters NOT perpendicular to the surface of the glass in one medium (such as air) and exits the glass in another medium (such as water)
Consider a glass pane. When is the angle at which a ray of light strikes the glass pane on one side not the same as the angle at which it exits the glass pane on the other side?
When the light strikes the glass in one medium (such as air) and exits the glass in another medium (such as water)
What is the evidence for the statement that white light is a composite of all the colors of the spectrum?
White light can be separated into all colors of the spectrum using a prism, and then these colors can be recombined to make white light.
Does the law of reflection hold for curved mirrors? Explain.
Yes. It is as if the curved mirror is made of many small plane mirrors at slightly different orientations to each other.
Choose the most correct definition of entropy below.
a measure of disorderedness
Which of the following correctly describes the fundamental source of all magnetic field? (Note: "fundamental" here means "elementary", that the object cannot be broken down into a simpler object which also produces a magnetic field.)
a moving electric charge
Answer this question regarding magnetic fields generated by a current. If you are looking at a straight line of current coming towards you, the magnetic field lines due to this current will appear as ...
circles around the current going counter-clockwise.
Choose the statement below which most correctly defines or describes "heat".
one of the mechanisms of energy transfer
