SCIN 111 Exam 2 - Chapters 6,7,8, and 9
Electric charge
-fundamental quantity underlying electric force and all electric phenomena -comes in two kinds: 1) positive such as protons 2) negative such as electrons
Difference and similarities between gravitational and electrical forces
-gravity only attracts. electricity can both attract and repel -both forces can act between things that are not in contact with each other -both forces act in a straight-line direction between masses or charges -a force field surrounds both: gravitational field for mass and electric field for charge
High specific heat capacity of water
-has higher capacity for storing energy than almost any other substance -involves various ways that energy can be absorbed -increase the jiggling motion of molecules, which raises the temperature -increase the amount of internal vibration or rotation within the molecules, which becomes potential energy and doesn't raise temperature -then water molecules can absorb energy without increasing translational kinetic energy
Quantity of Heat
-heat is energy in transit, measured in units of energy- joules or calories
Kilocalorie
-heat unit in labeling food -one kilocalorie or Calorie (with a capital C) is the heat needed to changed the temperature of 1 kilogram of water by degree Celsius
Boiling
-heating warms the water from below -boiling cools the water from above
Condensation Application
-if you're chilly outside the shower stall, step back inside and be warmed by the condensation of the excess water vapor in the shower -evaporation cools you. condensation warms you!
Conservation of Change
-in any charging process, no electrons are created or destroyed -electrons are simply transferred from on material to another
Electric potential difference
-in chemical batteries 1) work by chemical disintegration of zinc or lead in acid 2) energy stored in chemical bonds is converted to electric PE
The Transformer - Boosting or Lowering Voltage
-input coil or wire - primary powered by AC voltage source -output could of wire - secondary connected to external circuit -both wound on a common iron core -then magnetic field of primary passed through secondary -uses ac in one coil to induce ac in second coil
Safety fuses
-wires melt when current is excessive -connected in series along supply line to prevent overloading -commonly replaces by circuit breakers
Parallel circuits and overloading
Homes are wired in parallel. As more and more devices are connected, more current moves through the wires. Each device can carry a certain amount of current before overheating. Excessive current can result in a fire
Reflection of radiant energy
-darkness is often due to reflection of light back and forth many times partially absorbing with each reflection -good reflectors are poor absorbers
Heat
-defined as a flow of thermal energy due to a temperature difference -natural direction of flow is from a higher-temperature substance to a lower-temperature substance
Heat - hot stove
-1 liter of water in left pot and 2 liters of water in the right pot -both pots absorb the same quantity of heat -temperature increases three times as much in the pot with the smaller amount of water -(temperature of the water depends on how much water in the container)
Celsius scale
-Named after Anders Celsius -zero for freezing point of water -100 for boiling point of water
Fahrenheit scale
-Named after G.D. Fahrenheit -32 for freezing point of water -212 for boiling point of water
Kelvin scale
-Named after Lord Kevin -273 for freezing point of water -373 for boiling point of water -absolute zero at -273
Parallel circuit
-a branched pathway is formed for the flow of electrons -a break in any path doesn't interrupt flow in other paths -a device in each branch operates independently of the others -total current in the branches add
Entropy
-a measure of the disorder of a system -whenever energy freely transforms from one form to another, the direction of transformation is toward a state of greater disorder and, therefore, toward one of greater entropy -the greater the disorder --> the higher the entropy -energy tends to degrade and disperse with time -the total amount of entropy in any system tends to increase with time
Series circuit
-a single-pathway circuit for electron flow -a break anywhere in the path results in an open circuit; electron flow ceases -total resistance adds, more devices, less current
Expansion of Metal Application
-a thermostat -when the bimetallic coil expands, the ball of liquid mercury rolls away from the electrical contracts and breaks the electrical circuit -when the coil contracts, the circuit is complete
Electric circuits
-any closed path along which electrons can flow for continuous flow - no gaps (such as an open electric switch) -devices connect to a circuit in one of two ways: 1) series 2) parallel
Newton's Law of Cooling
-approximately proportional to the temperature difference (delta) T between the objects and its surroundings -in short: rate of cooling ~ (delta) T EX) hot apple pie cools more quickly in a freezer than if left on the kitchen table -applies to rate of warming -object cooler than its surroundings warm up at a rate proportional to (delta) T EX) frozen foods warm quicker in a warm room than in a cold room
Water and Ice Application
-as water cools in winter, it becomes more dense and sinks. sinking continues until the entire pond is at 4 C -then, as water at the surface is cooled further, it floats on top and can freeze -once ice is formed, temperatures lower than 4 C can extend down into the pond
Electric Force and Charge
-atom is normally electrically neutral -same number of electrons outside nucleus as protons in the nucleus -outer electrons in metals 1) loosely bound 2) can move freely 3) can flow 4) can join with other atoms -atom losing 1 or more electrons --> positive ion -atom gaining 1 or more electrons --> negative ion -amount of work varies in pulling electrons from atoms of different substances 1) very little for metals and other good conductors 2) more work for rubber and other good insulators
Electric Field Induction
-basic to electromagnetic induction is that electric and magnetic fields can induce each other 1) an electric field is induced in any region of space in which a magnetic field is changing with time or 2) a magnetic field is induced in any region of space in which an electric field is changing with time
Cooling of water winter
-becomes more dense and sinks -continues sinking until entire pond is 4 C
Expansion of Metal
-bimetallic strip (brass and iron welded together) -when the strip is heated, brass expands more than iron -when cooled, brass contacts more than iron -due to this behavior, the strip bends as shown
Magnetic Domains
-clustered regions of aligned atoms -oriented in random fashion - magnetic fields produced by each can cancel the field of other -when oriented in one direction, then the substance containing them is a magnet -magnet strength depends on number of magnetics domains that are aligned
Good conductors
-composed of atoms with "loose" outer electrons -known as poor insulators -EX) all metals to varying degrees
Processes of thermal energy transfer
-conduction -convection -radiation
Electric Currents and Magnetic Fields
-connection between electricity and magnetism -magnetic field forms a pattern of concentric circles around a current-carrying wire 1) when current reverses direction, the direction of the field lines reverse
Galvanometer
-current-indicating device named after Luigi Galvani -called ammeter when calibrated to measure current (amperes) -called voltmeter when calibrated to measure electric potential (volts)
Electric shock
-damaging effects of shock result from current passing through the body -electric potential difference between one part of your body and another part depends on body condition and resistance, which can range from 100 ohms to 500,000 ohms
calorie
-defined as the amount of heat needed to raise the temperature of 1 gram of water by 1 celsius degree -4.19 joules = 1 calorie -so 4.19 joules of heat will changes that temperature of 1 gram of water by 1 celsius degree
Specific Heat Capacity
-defined as the quantity of heat required to change the temperature of 1 unit mass of a substance by 1 degree -thermal inertia that indicates the resistance of a substance to a change in temperature -sometimes simply called specific heat -substances have their own specific heat capacities EX) filling in a hot apple pie has a greater specific heat capacity than the crust
Poor conductors
-delay the transfer of heat -known as good insulators -EX) wood, wool, straw, paper, styrofoam, cork, liquid, gases, air, or materials with trapper air
Electrical Resistance
-describes how well a circuit component resists the passage of electric current -defined as the ratio of energy-source voltage to the current moving through the energy receiver -measured in ohms after 19th century German physicist Georg Simon Ohm
Electric meters
-detect electric current EX) magnetic compass, compass in a coil of wires
Electromagnetic Induction
-discovered by Faraday and Henry -voltage is induced with charge of magnetic field strength in a coil of wire -induced voltage can be increased by 1) increasing the number of loops of wire in a coil 2) increasing the speech of the magnet entering and leaving the coil a) slow motion produces hardly any voltage b) rapid motion produces greater voltage
Water between 0 C and 4 C
-does not expand with temperature -as temperature of 0 C water rises, contradiction occurs due to melting of ice crystals in water -contraction of water continues until 4 C
Insulation
-doesn't prevent the flow of internal energy -slows the rate at which internal energy flows EX) rock wool or fiberglass between walls slows the transfer of internal energy from a warm house to a cool exterior in winter, and the reverse in summer
Thermal Expansion
-due to rise in temperature of a substance; molecules jiggle faster and move farther apart -most substances expand when heated, and contract when cooled EX) railroad tracks closely laid on winter days expand and buckle in hot summer
Electric Potential
-electric potential energy per charge -energy that a source provides to each unit of charge Electric potential = (electric potential energy) / (charge) -electric potential and voltage are one and the same -unit of measurement is the volt 1 volt = (1 joule) / (coulomb)
Magnetic fields are produced by two kinds of electron motion
-electron spin 1) main contributor to magnetism 2) pair of electrons spinning in same direction creates a stronger magnet 3) pair of electrons spinning in opposite direction cancels magnetic field of the other -electron revolution
Climate Change
-energy absorbed from the Sun -part reradiated by Earth as longer-wavelength terrestrial radiation -terrestrial radiation absorbed by atmospheric gases and re-emitted as long-wavelength terrestrial radiation back to Earth -reradiated energy unable to escape, so warming of Earth occurs -long-term effects on climate are of present concern
Electric potential energy
-energy possessed by a charged particle due to its location in an electric field -work is required to push a charged particle against the electric field of a charged body 1) the spring has more elastic PE when compressed 2) the small charge similarly has more PE when pushed closer to the charged sphere. In both cases, the increased PE is the result of work input -released particle accelerates away from the sphere - electric PE changes to KE -batteries and generators pull negative charges away from positive ones, doing work to overcome electrical attraction -the amount of work depends on number of charges and separation distance -work done by a battery or generator is then available to a circuit as electrical PE
Emission of radiant energy
-every object above absolute zero radiates -from the Sun's surface comes light, or solar radiation -from the Earth's surface is terrestrial radiation in the form of infrared waves below our threshold of sight
Expansion of Water
-expands when it turns to ice. ice has open-structured crystals resulting from strong bonds at certain angles that increase it volumes. this makes ice less dense than water -volume changes for a 1-gram sample of water
Coulomb's Law
-for a pair of charged objects much smaller than the distance between them, force between them varies directly as 1) the product of their charges 2) and inversely as the square of the separation distance -unit of charge is measured in coulombs, C. -the charge of an electron is the fundamental charge = 1.6 X 10 (^9) N X m(^2)/C(^2) 1) like signs of charge - force is repulsion 2) unlike signs of charge - force is attraction
Magnetic Force
-force of attraction or repulsion between a pair of magnets depends on which end of the magnet is held near the other -behavior similar to electrical forces -strength of interaction depends on the distance between the two magnets
Sublimation
-form of phase change directly from solid to gas EX) dry ice (solid carbon dioxide molecules), mothballs, frozen water
Field Induction
-light is produced by the mutual induction of electric and magnetic fields -speed of light is the speed of emanation of these fields 1) too slow, the regenerating fields die out 2) too fast, fields build up in a crescendo of ever-increasing energy 3) at speed c, just right! And, there is light!
Magnetic Poles
-magnetic poles are in all magnets: 1) you can't have one pole without the other 2) no single pole known to exist EX) simple bar magnet - poles at the two ends -give rise to magnetic force -two types interacting with each other 1) north pole (north-seeking pole) 2) south pole (south-seeking pole)
Electric conductors
-materials that allow easy flow of charged particles 1) outermost electrons of atoms attracted loosely and are easily dislodged - as in metals 2) innermost electrons strongly attracted to nucleus
Phases of Matter
-matter exists in the three common phases: solid, liquid, and gas (a fourth phase of matter is plasma) -when matter changes from on phase to another, energy is transferred
Thermometer
-measures temperature by expansion or contraction of a liquid (mercury or colored alcohol) -reading occurs when this and the object reach thermal equilibrium (having the same average kinetic energy per particle) -infrared operate by sensing IR radiation
Evaporation process
-molecules in liquid move randomly at various speeds, continually colliding with one another -some molecules gain kinetic energy while others lose kinetic energy during collision -some energetic molecules escape from the liquid and become gas -average kinetic energy of the remaining molecules in the liquid decreases, resulting in cooler water
Charge Polarization
-molecules in solids can't move from their relatively stationary positions, but their "centers of charge" can move -this distortion of charge in the atom or molecule is electric polarization
Greenhouse Effect
-names for a similar temperature-raising effect in florists' greenhouses -short-wavelength radiation from the Sun is transmitted through the glass -long-wavelength reradiated energy is not transmitted out through the glass and is trapped inside
Electrons
-negative electric charges -repel negatives, but attract positives
Transformer Power
-neglecting heat losses, power into a transformer = power out of transformer (voltage X current) primary = (voltage X current) secondary
Electric Field
-occupies the space that surrounds any charges object -is a vector quantity (having magnitude and direction) -magnitude of field at any point is force per unit charge -obeys the inverse-square law for a point source
Magnetic fields
-occupy the space around a magnet -produced by moving electric charges -field shape revealed by magnetic field lines that spread from one pole, curve around magnet, and return to other pole 1) lines closer together --> field strength is greater
Heat Transfer: Conduction
-occurs predominately in solids where the molecules remain in relatively restricted locations -when you stick a nail into ice, does cold flow from the ice to your hand, or heat from your hand to the ice?
Generator
-opposite of a motor -converts mechanical energy into electrical energy via coil motion -produces alternating voltage and current
Condensation process
-opposite of evaporation -warming process from a gas to a liquid -gas molecules near a liquid surface are attracted to the liquid -they strike the surface with increased kinetic energy, becoming part of the liquid
Cooling by expansion
-opposite to the warming that occurs when air is compressed EX) the "cloudy" region above hot steam issuing from the nozzle of a pressure cooker is cool to the touch (a combination of air expansion and mixing with cooler surrounding air)
Evaporation Application
-piges have no sweat glands and therefore cannot cool by the evaporation or perspiration -instead, they wallow in mud to cool themselves
Protons
-positive electric charges -repel positives, but attract negatives
Voltage Sources
-potential difference exists when ends of electrical conductor are at different electric potentials -batteries and generators are common voltage sources -charges in a conductor tend to flow from higher potential to lower potential. The flow of charges persists until both ends reach the same potential. Without potential difference, no flow of charge EX) water from a higher reservoir to a lower one - flow continues until no difference -no flow of charge occurs when potential difference is zero
Convection Currents
-produced by unequal heating of land and water -during the day, warm air above the land rises, and cooler air over the water moves in to replace it -at night, the direction of air flow is reversed
Boiling Process
-rapid evaporation occurs beneath the surface of a liquid -evaporation beneath the surface forms vapor bubbles -bubbles rise to the surface -if vapor pressure in the bubble is less than the surrounding pressure, then the bubbles collapse -hence, bubbles don't form at temperatures below boiling point when vapor pressure is insufficient
Electric Power
-rate at which electric energy is converted into another form -in equation form: power = current X voltage -in units: watts EX) 100-watt lamp draws 0.8 ampere
Ohm's Law
-relationship between current, voltage, and resistance -current in a circuit varies in direct proportion to the potential difference (voltage) and inversely with the resistance
Second Law of Thermodynamics
-restates directions of heat flow: heat never spontaneously flows from a cold substance to a hot substance EX) in summer, heat flows from the hot air outside into the cooler interior of a dwelling. in winter, heat flows from the warm inside to the cold exterior -heat can flow from cold to hot only when work is done on the system or by adding energy from another source (as in heat pumps and air conditioners, where the direction of heat flow isn't spontaneous)
Conduction Application
-snow patterns on the roof of a house show areas of conduction and insulation -bare parts show where heat from inside has conducted through the roof and melted the snow
Electric Current
-sustained electric current requires suitable voltage source 1) works by pulling negative charges apart from positive ones (available at the terminals of a battery or generator) 2) energy per charge at terminals provides the difference in potential (voltage) to provide "electrical pressure" to move electrons through a circuit -is the flow of electric charge -in metal - conduction electrons -in fluids - positive and negative ions -measured in amperes -actual speed of electrons is slow through a wire, but electric signal travels near the speed of light
Thermal Energy in a sparkler
-temperature of sparks very high (2000 C) -lot of energy per molecule of spark -total energy is small due to relatively few molecules per spark -low transfer of energy
Absorption of Radiant Energy
-the ability of a material to absorb and radiate thermal energy is indicated by its color -good absorbers and good emitters are dark in color -poor absorbers and poor emitters are reflective or light in color
Why a charged rubber balloon sticks to a wall
-the charges balloon induces polarization of molecules or atoms in the wall. Negative charges on balloon pull positive sides of molecules near it. Hence a slightly positive induced surface charge on the wall -the balloon sticks
Thermal Expansion Application
-the extreme heat of a summer day cause the buckling of these railroad tracks -this gap in the roadway of a bridge is called an expansion joint; it allows the bridge to expand and contract
Faraday's Law
-the induced voltage in a coil is proportional to the number of loops, multiplied by the rate at which the magnetic field changes within those loops -amount of current produced by electromagnetic induction is dependent on 1) resistance of the coil 2) circuit that it connects 3) induced voltage
Absolute zero / zero K
-the lowest limit of temperature at (-273) C -molecules have lost all available kinetic energy -as temperature of a gas changes, volume of a gas changes -at 0 C with pressure constant, volume changes by 1/273 for each degree Celsius
Emission and Absorption
-the surface of any material both absorbs and emits radiant energy -when a surface absorbs more energy than it emits, it is a net absorber, and temperature tends to rise -when a surface emits more energy than it absorbs, it is a net emitter, and temperature tends to fall
Pressure Cooker
-the tight lid of a pressure cooker holds pressurized vapor above the water surface, which inhibits boiling -in this way, the boiling point of water is greater than 100 C
Evaporation-Condensation toy
-the toy drinking bird operates by the evaporation of ether inside its body and by the evaporation of water from the outer surface of its head. the lower body contains liquid ether, which evaporates at room temperature 1) vaporizes 2) creates pressure, ether goes up the tube 3) tips over, condensed ether runs back to body 4) each pivot wets the head and the cycle repeats
Factors affecting electrical resistance
-thin wires resist electrical current more than thicker wires -long wires offer more electrical resistance -materials of wire: 1) copper has a low electrical resistance, so it is used to make connecting wires 2) rubber has an enormous resistance, so it is used in electrical insulators -temperature: 1) higher temperature (greater jostling of atoms), greater resistance
Transformers Everywhere
-this common transformer lowers 120V to 6V or 9V. it also converts AC to DC by means of a diode inside -a common neighborhood transformer that typically steps 2400V down to 240V
Convection
-transfer of heat involving only bulk motions of fluids EX) visible shimmer of air above a hot stove or above asphalt on a hot day
Prongs on electric plugs and sockets:
-two flat prongs for the current-carrying double wire, one part live and the other neutral -third prong is longer and the first to be plugged into socket; path to ground prevents harm to user if there is an electrical defect in the appliance
Climate Change and the Greenhouse Effect
-understanding the greenhouse effect requires two concepts: 1) all things radiate at frequency (and therefore wavelength) that depends on the temperature of the emitting object 2) transparency of things depends on the wavelength of radiation
Field lines
-used to visualize electric field -show direction of electric field - away from positive and toward negative -show intensity of electric field: 1) bunched together --> field is strongest 2) lines farther apart --> field is weaker
Electric Grid uses Transformers
-voltage generated in power stations is stepped up with transformers prior to being transferred across the country by overhead cables -then other transformers reduce the voltage before supplying it to homes, offices, and factories
Reason warm air rises
-warm air expands, becomes less dense, and is buoyed upward -air rises until its density equals that of the surrounding air -EX) smoke from a campfire rises and brands with the surrounding cool air
Heat Transfer: Radiation
-wavelength of radiation is related to the frequency of vibration -low frequency vibrations --> long waves -high frequency vibrations --> short waves
Magnetic Force and Levitation
-when an upward magnetic force is greater than gravity, then an object can levitate -a magnetically levitated vehicle is shown in the figure to the right - a magplane -no friction, no vibrations
First Law of Thermodynamics
-when heat flows to or from a system, the system gains or loses an amount of heat equal to the amount of heat transferred -more specifically, heat added = increase internal energy + external work don't by the system -energy can neither be created nor destroyed
Emission and Absorption
-whether a surface is a net absorber or net emitter depends on whether its temperature is above or below that of its surroundings -a surface hotter than its surroundings will be a net emitter and tends to cool -a surface colder than its surroundings will be a net absorber and tends to warm
Answer: A
A motor and a generator are a) similar devices b) very different devices with different applications c) forms of transformers d) energy sources
Answer: B
A spectacular classroom (or home) demo is placing a soda-pop can with a bit of water in it on a hot stove. Soon steam comes from the opening. Invert the can into a bath of water and atmospheric pressure crushes the can. The key to this dramatic whopping of the can is mainly a) temperature reduction of the steam in the can b) rapid condensation of steam in the can c) reduced pressure due to cooling of steam in the can d) increase in atmospheric pressure on the can
Answer: A
A step-up transformer in an electrical circuit can step up a) voltage b) energy c) both A and B d) neither A nor B
Answer: C
A weak and strong magnet repel each other. The greater repelling force is by the a) stronger magnet b) weaker magnet c) both the same d) none of the above
Answer: B
According to Coulomb's law, a pair of particles that are placed twice as far apart will experience forces that are a) half as strong b) one quarter as strong c) twice as strong d) four times as strong
Answer: C
Although warm air rises, why are mountaintops cold and snow covered, while the valleys below are relatively warm and green? a) warm air cools when rising b) there is a thick insulating blanket of air above valleys c) both of the above d) none of the above
Answer: C
An electromagnet can be made stronger by a) increasing the number of turns of wire b) increasing the current in the coil c) both A and B d) none of the above
Answer: C
Anette heats a metal ring that has the same inner diameter as the diameter of the metal ball. When the ring is hot, the room-temperature ball a) fits into the hole as before b) no longer fits into the hole c) fits into the hold with more room to spare d) none of these
Answer: D
Consider a lamp powered by a battery. Charge flows a) out of the battery and into the lamp b) from the negative terminal to the positive terminal c) with a slight time delay after closing the switch d) through both the battery and the lamp
Magnetic Force in Space
Earth's magnetic field deflects many charged particles that make up cosmic radiation
Answer: A
Electric potential energy is measured in joules. Electric potential, on the other hand (electric potential energy per charge), is measured a) in volts b) in watts c) in amperes d) also in joules
Answer: A
If Earth radiated more energy than it absorbs from the Sun, Earth's average temperature would a) decrease b) increase c) likely not change d) none of these
Answer: B
If a good absorber of radiant energy were a poor emitter, its temperature compared with its surroundings would be a) lower b) higher c) unaffected d) none of the above
Answer: C
If you hold one end of metal bar against a piece of ice, the end in your hand will soon become cold. Does cold flow from the ice to your hand? a) yes b) in some cases, yes c) no d) in some cases, no
Answer: A
It is commonly thought that a can of beverage will cool faster in the coldest part of a refrigerator. Knowledge of Newton's law of cooling a) supports this knowledge b) shows this knowledge is false c) may or may not support this knowledge d) may or may not contradict this knowledge
Answer: B
The magnetic force on a moving charged particle can changes the particle's a) speed b) direction c) both A and B d) neither A nor B
Answer: A
The mutual induction of electric and magnetic fields can produce a) light b) energy c) sound d) none of the above
Answer: C
The quantity of heat needed to raise the temperature of a certain substance a specific amount is 1 Calorie. This is the same amount of energy as a) 1000 calories b) 4.19 joules c) both of these d) neither of these
Answer: A
The resistance you feel when pushing a piece of iron into a coil involves a) repulsion by the magnetic field you produce b) energy transfer between the iron and coil c) Newton's third law d) resistance to domain alignment in the iron
Answer: A
There is twice as much molecular kinetic energy in 2 liters of boiling water as in 1 liter of boiling water. Which will be the same for both? a) temperature b) thermal energy c) both of the above d) none of the above
Electric force
a fundamental force of nature can attract some objects and repel others
Answer: A
When a hot cup is filled with cold water, the direction of heat flow is a) from the cup to the water b) from the water to the cup c) random, in no particular direction d) nonexistent
Answer: A
When a liquid changes phase to a gas, it a) absorbs energy b) emits energy c) neither absorbs nor emits energy d) becomes more conducting
Answer: C
When a liquid is brought to a boil, the boiling process tends to a) resist a further change of phase b) heat the liquid c) cool the liquid d) radiate energy from the system
Answer: B
When a sample of 0 C water is heated, it first a) expands b) contracts c) remains unchanged d) not enough information
Answer: A
When a sample of 4 C water is cooled, it a) expands b) contracts c) remains unchanged d) not enough information
Answer: A
When stringing telephone lines between poles in the summer, it is advisable to allow the lines to a) sag b) be taut c) be close to the ground d) allow ample space for birds
Answer: C
When thermal insulation, such as spun glass or rock wool, is places beneath the roof of a house, then in cold weather the insulation will a) create heat to warm the house b) keep the cold from coming through the rood c) slow the flow of heat from inside the house to the outside d) stop the flow of heat from inside the house to the outside
Answer: A
When two identical lamps in a circuit are connected in parallel, the total resistance is a) less than the resistance of either lamp b) the same as the resistance of each lamp c) less than the resistance of each lamp d) none of the above
Answer: A
When work is done on a system, compressing air in a tire pump for example, the temperature of the system a) increases b) decreases c) remains unchanged d) is no longer evident
Answer: A
When you brush Fido's fur and scrape electrons from it, the charge of Fido's fur is a) positive b) negative c) both A and B d) neither A nor B
Answer: B
When you buy a water pipe in a hardware store, the water isn't included. When you buy copper wire, electrons a) must be supplied by you, just was water must be supplied for a water pipe b) are already in the wire c) may fall out, which is why wires are insulated d) none of the above
Answer: A
When you double the voltage in a simple electric circuit, you double the a) current b) resistance c) both of the above d) neither of the above
Answer: A
Which has the higher specific heat, water or land? (water 20 C, land 25 C) a) water b) land c) both of the above are the same d) none of the above
Answer: B
Which is the better statement? a) a black object absorbs energy well b) an object that absorbs energy well is black c) both say the same thing, so both are equivalent d) both are untrue
Answer: D
Which of the following does NOT emit radiation? a) a lit fluorescent lamp b) a lit incandescent lamp c) a burned out incandescent lamp d) none of the above
Answer: A
Which of these statements is true? a) electric current is a flow of electric charge b) electric current is stored in batteries c) both are true d) neither are true
Answer: C
You heat a half-cup of tea and its temperature rises by 8 C. How much will the temperature rise if you add the same amount of heat to a full cup of tea? a) 0 C b) 2 C c) 4 C d) 8 C
Answer: A
Your garage gets messier each week. In this case, the entropy of your garage is a) increasing b) decreasing c) hanging steady d) nonexistent
Wave Frequency - Temperature
a) a low-temperature (cool) source emits primarily low-frequency, long wavelength waves b) a medium-temperature source emits primarily medium-frequency c) a high-temperature source emits primarily high-frequency, short wavelength waves
Equilibrium
a) in a mixture of ice and water at 0 C, ice crystals gain and lose water molecules at the same time. the ice and water are in the thermal equilibrium b) this gaining-and-losing process is inhibited when salt is added to the water. then with fewer water molecules at the interface, fewer enter the ice
AC
alternating current charges alternate in direction
Circuit breaker
automatic switch that turns off when the current is excessive
Superconductors
certain metals that acquire infinite conductivity (zero resistance) at temperatures near absolute zero
Evaporation
change of phase from liquid to gas
Magnetic Forces on Moving Charges
charged particles moving in a magnetic field experience a deflecting force - greatest when moving at right angles to magnetic field lines
Electric motor
different from galvanometer in that each time the coil makes a half rotation, the direction of the current changes in cyclic fashion to produce continuous rotation
DC
direct current charges flow in one direction
Specific heat affects climate
for Europeans, in addition to warm jet streams in the atmosphere, current in the Atlantic Ocean carries warm water northeast from the Caribbean regions and retains much of its internal energy long enough to reach the North Atlantic Ocean. Energy released is carried by westerly winds over the European continent
Solid
how fast particles move as they vibrate and jiggle in place
Liquid
how fast particles slide and jiggle past one another
Gas
how fast the gas particles are bouncing to and fro
Magnetic field intensity
increases as the number of loops increase in a current-carrying coil
When 0 C water freezes to become ice
largest volume and lowest density
Fundamental rule for electricity
like charges repel; unlike charges attract
Rule for magnetic forces between magnetic poles
like poles repel; opposite poles attract
Electric Insulators
materials having tightly bound electrons
Semiconductors
materials that are neither good conductors nor good insulators, whose resistance can be varied
Kinetic Theory of Matter
matter is made up of tiny particles (atoms or molecules) that are always in motion
Energy rating of food or fuel
measure by energy released when they are metabolized
Temperature
proportional to the average translational kinetic energy per particle in a substance
Thermodynamics
movement of heat
Neutrons
neutral electric charge
Third Law of Thermodynamics
no system can reach absolute zero
Ampere
one is the rate of flow of 1 coulomb of charge per second or 6.25 billion billion electrons per second
Emission of radian energy
peak frequency of radiation is proportional to the absolute temperature of the source
Transformer relationship
primary voltage/number of primary turns = secondary voltage/number of secondary turns
Water at 4 C
smallest volume and greatest density
Ice formation
temperatures lower than 4 C can extend down into pond
Generators and Alternating Curren
the frequency of alternating voltage induced in a loop is equal to the frequency of the changing magnetic field within the loop
Thermal Energy
the total energy (kinetic and potential) of the submicroscopic particles that make up matter
Radiation
transfer of energy via electromagnetic waves that can travel through empty space
Conduction
transfer of internal energy by electron and molecular collisions within a substance
Power Production
using Faraday and Henry's discovery of electromagnetic induction, Nikola Tesla and George Westinghouse showed that electricity could be generate in sufficient quantities to light cities
Further cooling of water at the surface
water floats on top and can freeze
