SCMH 1010 Exam #2
Which has a greater amount of entropy? Air at 0 C Air at 20 C Air at -20 C Air at 40 C
Air at 40 C
A calories is the amount of heat energy necessary to raise the temperature of one gram of water by one degree
Celsius
Water freezes at 0 in the --- temperature scale
Celsius
The person who defined the nature of the electrical force between two charged bodies was
Charles Coulomb
Who showed that electrical forces could be used to do work, i.e., demonstrated the first electrical generator?
Michael Faraday
electromagnet
a device composed of a coil of wire that produces a magnetic field whenever an electrical charge runs through the wire
wave
a traveling disturbance that carries energy from one place to another
Bats use high-pitched sound waves undetectable to human hearing to detect objects in their environment. This means the wavelength of sounds they use is
above 20,000 Hz
Gamma radiation is a shorter wavelength than: visible light microwaves x-rays radio waves all of the above
all of the above
AC
alternating current; favored by Nikola Tesla
ampere
amount of current that flows in a wire
Turning up the volume of music or speaking louder means that the sound wave has changed
amplitude
What aspect of a sound wave makes it seem loud to people hearing the sound?
amplitude
the height of a wave crest above the undisturbed portion is its
amplitude
a circuit consists of
an energy source, a closed path, and a device that uses electrical energy
temperature is
atomic movement (speed of molecules)
The dipole field is found in
bar magnets
A device that converts stored energy into the kinetic energy of electrons passing through an outside wire is called a(n)
battery
refraction
bent light
visible light of a high frequency is
blue
If you are standing in the path of a source of light that is moving toward you, the light you see will look -- than it would ordinarily
bluer
convection
bulk transfer of molecules
electromagnets are used in
buzzers, switches, and electric motors
The heat island effect in cities creates convection cells
by drawing in cool moist air from the suburbs
The amount of energy required to raise the temperature of one gram of water by 1 degree Celsius is a
calorie
In science, heat is commonly measured in what unit?
calories
heat is measured in
calories
The transfer of heat by direct atomic collisions is referred to as
conduction
What is the only way heat can be transferred within a solid piece of metal
conduction
a spoon in hot water is an example of
conduction
The transfer of heat by density - driven motion of gases or fluids is referred to as
convection
The transfer of heat by the bulk motion of gases or fluids is referred to as
convection
boiling a pot of water is an example of
convection
infrared radiation
converted to thermal energy at its destination
Which substance has the lowest specific heat capacity?
copper
The amount of electrons flowing in a specific direction is termed the
current
When electric charges are in motion we have
current
Voltage is calculated with the following formula
current x resistance
Albert A. Michaelson
demonstrated that light travels without a medium
parallel circuit
different loads are situated on different wire loops
an electric current flowing from a storage battery is
direct current
DC
direct current; favored by Thomas Edison
Ben Franklin
discovered electricity and invented the lightning rod
Hans Christian Oersted
discovered that magnetism and electricity are intimately related when he ran current through a circuit and a nearby compass moved
William Gilbert
discovered the poles in a dipole magnet
Entropy is the measure of a system's
disorder
wavelength
distance between crests (highest points of adjacent waves)
Radiation is heat transfer by
electromagnetic waves of radiation
Static electricity exists when there is an unbalance among the number of
electrons
the force that moves electrically charged objects toward and away from each other is
electrostatic force
entropy can go backward only if
extra energy is introduced
Of the types of radiation listed below, the only one that humans can detect is gamma rays infrared waves visible light x-rays none of the above
none of the above
frequency
number of wave crests that go by a given point every second
In the equation of Ohm's law, resistance is in the unit
ohms
One amp of electrical current is equal to
one coulomb of charge per second
A term that compares how vigorous atoms are moving in a substance is
temperature
Temperature is a measure of
the average kinetic energy of the atoms within a substance
Daniel Fahrenheit invented temperature scale for which 0 represented
the coldest temperature he could obtain for salt water
What direction does energy move in?
the direction of the wave
electric field
the force exerted on its surroundings by a charged object
electricity
the force that moves objects toward and away from eachother
when we hear a sound change from a higher to a lower pitch, this means
the frequency has changed
an efficient engine has
the least amount of disorder possible (the most work that the engine allows from the energy put in)
In a transverse wave
the motion of the medium is perpendicular to the motion of the wave
Why does lightning occur?
the negative charges in the cloud are attracted to the positive charges on the ground
The higher the frequency of a sound wave
the shorter the wavelength
The velocity of all electromagnetic radiation is
the speed of light
Coulomb's law states that the force of static electricity between two objects is inversely proportional to
the square of the distance between the objects
Fahrenheit =
(1.8 x C) + 32
Celcius =
(F - 32) / 1.8
Which of these represents the coldest temperature? 0 degree Celsius Freezing point of CO2 (dry ice) 0 degrees Kelvin -100 degrees Celsius 0 degrees Fahrenheit
0 degrees Kelvin
gamma rays
0.1 nm - 1 x 10^-12 m
A particular electrical appliance requires 30 W. When it is connected to a power source that provides 120 V, the current in the circuit is
0.25 A
radiowaves
1 KHz - 1 MHz
herts (HZ) =
1 cycle / 1 second
microwaves
1 m - 1 mm
infrared radiation
1 mm - 1 micron
2nd law of thermodynamics
1. heat does not flow spontaneously from hot to cold. 2. no engine can exclusively convert heat to work 3. every isolated system tends toward disorder
How much amperage will be moving through a wire if it has a resistance of 12 ohms and is carrying 120 V?
10 Amps
x-rays
100 nm - 0.1 nm (smaller than an atom)
The voltage across a resistor is 20 and the current through it is 10 A. What is the resistance o the resistor?
2 ohms
The current through a 5 ohm resistor is 0.40 A. What is the voltage across the resistor?
2.0 V
How fast can light travel in one second, if it is moving through a vacuum?
300,000 km
all electromagnetic waves travel at
300,000 km/sec
In the Kelvin scale, water boils at
373 K
twenty calories of heat energy will raise the temperature of five grams of water
4 C
ultraviolet radiation
400 nm - 100 nm
Which sound wave frequency is outside the range of a human's ability to detect? 200 Hz 5 Hz 2000 Hz 10000 Hz 20 Hz
5 Hz
If the temperature of an object changes by 5 C then it also changes by
5 K (kelvin)
The current in a circuit is 0.5 A and the voltage across it is 12 V. The power being supplied by the source is
6 W
1 coulomb =
6.3 x 10^18 electrons
visible light
700 nm - 400 nm
k =
8.99 x 10^9
Approximately how much power is consumed per hour by an electric stove drawing 40 amps? (The stove is plugged into a 240 volt wall socket).
9.6 kW/hr
which of the following statements is not consistent with the second law of thermodynamics? all isolated systems will tend to remained ordered indefinitely heat will not flow spontaneously from a cold body to a hot body no engine is 100% efficient in converting energy to work the evolution of more complicated forms of life on earth does not annul the second law
All isolated systems will tend to remain ordered indefinitely
The unit for electric current is what?
Amps
electrical current is measured in
Amps
A bar magnet is magnetic even when no electric current is passing through it. Why?
Bar magnets take advantage of the electrons moving around in atoms to create a magnetic field.
the historical figure who demonstrated that lightning was electrical in nature was
Benjamin Franklin
A car converts energy and therefore represents a system. If gasoline is the material input, what is the material output?
CO2 emissions to the atmosphere
DC refers to
Direct current
the increase in frequency of an approaching source of electromagnetic radiation is termed to
Doppler effect
Some migratory birds use the following to guide them on long flights lightning static electricity earth's magnetic field electrical signals from the Earth
Earth's magnetic field
Which is more powerful? The force of gravity or electrical force?
Electrical force
In what way does Newton's law of universal gravitation differ from Coulomb's law?
Electrical forces can be either attractive or repulsive, while gravity is only attractive
Luigi Galvani
Electrical stimulation of the nerve in a frog's leg produced contraction of the leg muscle
electric motors
Employ a pair of permanent magnets and a rotating loop of wire inside the poles of the magnets
Michael Faraday
English chemist who created the first simple electric motor and the first dynamo
Which statement best represents the second law of thermodynamics? Heat will not flow spontaneously from a hot to a cold body. Scientists have constructed an engine that does nothing but convert heat to useful work. The total amount of energy in the universe is constant Every isolated system becomes more disordered with time. Energy may change from one form to another over and over again.
Every isolated system becomes more disordered with time.
Coulomb's law
F = K x (q1q2/d^2)
Another way of stating the Second Law of Thermodynamics is which of the following? In order to decrease the entropy of a system, work must be done on it by an external agent. It is impossible to decrease the entropy of a system In order to increase the entropy of a system, work must be done on it by an external agent. The entropy of any system remains constant or increases.
In order to decrease the entropy of a system, work must be done on it by an external agent.
Who authoritated entropy?
Ludwig Boltzmann
Name Electromagnetic Waves long to short
Radiowaves, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays
Conductors are materials with relatively low
Resistance
Which of the following is totally a longitudinal wave?
Sound
Which of the following is the definition of a calorie?
The amount of heat required to raise the temperature of 1 g of water initially at room temperature by 1 C
What is "heat death"?
The notion that the earth will ultimately be destroyed when all heat becomes heat waste
efficiency =
[(T hot - T cold) / T hot ] x 100
The Doppler effect decribes
change in a wave frequency when source or receiver is moving
Electric fields and electric currents can be produced by
changing magnetic fields
what causes the northern lights?
charged particles streaming from the sun can emit light when they interact with a magnetic field
heat is
energy in motion (amount of energy capable to do work)
radiation
energy that doesn't need a travel medium
A system that moves toward a higher state of order also moves toward a lower state of
entropy
All isolated systems will spontaneously tend toward disorder. This phenomenon is referred to as
entropy
Freezing ice from liquid water is an example of going to a lower state of
entropy
What are some things used to insulate homes today?
fiberglass, double paned windows, sheets of styrofoam
static electricity
force/energy resting on an object
Which property of electromagnetic waves is measured in Hertz?
frequency
objects from which electrons are removed
gain a positive charge
Which of the following has the shortest wavelength? fm radio waves am radio waves microwaves gamma rays
gamma rays
Sound waves with low frequencies:
have low pitches
amplitude
height of the wave crest above the undisturbed portion
heat will only flow spontaneously from
hot to cold
electrical resistance
how hard it is to push electrons through wires
cats' eyes are more sensitive to --- than humans'
infrared waves
Alessandro Volta
invented the battery
In a longitudinal wave, the motion of the medium
is parallel to the direction of the wave
The collection of lines that map out the directions in which compass needles would point is called a(n)
magnetic field
entropy is
measure of disorder
In his famous experiment of the late 1700s, Charles Coulomb
measured the force of the electric charge in objects
which of the following materials has the highest thermal conductivity? wood metal air fur
metal
Line of sight communications and radar rely heavily on what type of electromagnetic wave?
microwaves
Absolute zero is defined as the temperature a which
molecular and atomic vibration is zero; all heat extracted
You add heat to a solid and cause it to melt. The resulting configuration is
more disordered and at higher entropy
longitudinal wave
motion is in the same direction as the wave
transverse waves
motion is perpendicular to wave direction
conduction
movement of heat by atomic scale collision
Which of the following can produce magnetic fields?
moving electrical charges
Lazzaro Spallanzani
mutilated bats to find out that they locate food through hearing
load
power = v x c
voltage
pressure produced by the energy source
The standard use to calibrate Celsius thermometers is
pure water
Sunlight hitting dark roof tiles would and heating up a house would be an example of
radiation
The transfer of heat in the form of electromagnetic waves is called
radiation
a fire transfers most of its heat by
radiation
a fireplace or space heater is an example of
radiation
Energy can be transferred through a vacuum by
radiation only
visible light of a low frequency is
red
When light passes through a transparent material, its direction is usually changed slightly. This is called
refraction
Another word for constructive interference is
reinforcement
As energy is transferred from one trophic level to the next
some energy is always lost in the form of heat
The measure of the ability of a material to absorb heat is referred to as its
specific heat capacity
Which of the following is the same for all kinds of electromagnetic waves?
speed
velocity
speed and direction of wave crest
Through which material will heat be conducted the best?
steel
Maxwell's Equations
there are no magnetic monopoles in nature Coulomb's law: like charges repel, unlike attract magnetic phenomena can be produced by electrical effects electrical phenomena can be produced by magnetic effects
The measure of the quantity of heat contained in an object is referred to as its
thermal energy
period
time between adjacent waves, inverse of frequency (1 second / 1 wave)
The fundamental difference between electromagnetic waves and other types of waves is that electromagnetic waves:
transfer energy without transferring mass
electricity and magnetism are
two aspects of one force
series circuit
two or more loads are linked along a single loop of wire
Which type of radiation can be used to sterilize medical equipment?
ultraviolet radiation
Ohm's Law
v = c x r
wavelength formula
v = lamba x f
Ohm's Law states
voltage = current x resistance
what substance has the highest specific heat capacity?
water
absorption
wave and energy are absorbed
transmission
wave passes through matter
The distance between crests in a wave is its
wavelength
What are the properties of a wave
wavelength, frequency, amplitude, period, and velocity
constructive interference
waves act together (amplitude is increased)
scattering
waves are absorbed and reemitted (disuse scattering and reflection)
destructive interference
waves cancel each other out
human eyes are most sensitive to this color
yellow
Which device would most likely be running on DC electricity?
your cell phone