Download Electrostatic Mock Test 1 Charges 1. ____ are the charged parts of

Electrostatic Mock Test 1
Charges
1. ____ are the charged parts of an atom.
a. Only electrons
d. Electrons and neutrons
b. Only protons
e. Electrons and protons
c. Neutrons only
f. Protons and neutrons
2. TRUE or FALSE:
An object which is positively charged contains all protons and no electrons.
3. TRUE or FALSE:
An object which is negatively charged could contain only electrons with no accompanying protons.
4. TRUE or FALSE:
An object which is electrically neutral contains only neutrons.
5. Respond to the following student statement:
"A positively charged object is an object which has an excess of positive electrons."
6. Consider the graphic at the right of a neutral oxygen atom.
a. Explain what must happen in order for the oxygen atom to become
negatively charged.
b. Explain what must happen in order for the oxygen atom to become positively charged.
7. Electrical forces ____.
a. can cause objects to only attract each other
b. can cause objects to only repel each other
c. can cause objects to attract or repel each other
d. have no affect on objects
8. Two objects are charged as shown at the right. Object X will ____ object Y.
a. attract
b. repel
c. not affect
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Electrostatic Mock Test 2
Conductors & Insulators
1. One of these isolated charged spheres is copper and the
other is rubber. The diagram at the right depicts the
distribution of excess negative charge over the surface of
two spheres. Label which is which and support your
answer with an explanation.
2. Which of the following materials are likely to exhibit more conductive properties than insulating
properties? _____ Explain your answers.
a. rubber
b. aluminium
c. silver
d. plastic
e. wet skin
3. A conductor differs from an insulator in that a conductor ________.
a. has an excess of protons
b. has an excess of electrons
c. can become charged and an insulator cannot
d. has faster moving molecules
e. does not have any neutrons to get in the way of electron flow
f. none of these
4. Suppose that a conducting sphere is charged positively by some method. The charge is initially
deposited on the left side of the sphere. Yet because the object is conductive, the charge spreads
uniformly throughout the surface of the sphere. The uniform distribution of charge is explained by
the fact that ____.
a. the charged atoms at the location of charge move throughout the surface of the sphere
b. the excess protons move from the location of charge to the rest of the sphere
c. excess electrons from the rest of the sphere are attracted towards the excess protons
5. When an oil tanker car has arrived at its destination, it prepares to empty its fuel into a reservoir
or tank. Part of the preparation involves connecting the body of the tanker car with a metal wire to
the ground. Suggest a reason for why is this done.
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Electrostatic Mock Test 3
Charge Interactions
1. Two objects are shown at the right. One is neutral and the other is
negative. Object X will ____ object Y.
a. attract
b. repel
c. not affect
2. Benjamin Tesla is investigating the charge on several objects and makes the following findings.
Object C
attracts B
Object D
repels C
Object E
attracts D
Object F
attracts A
repels F
Benjamin knows that object A is negatively charged and object B is electrically neutral. What can
Benjamin Tesla definitively conclude about the charge on objects C, D, E, and F? Explain.
3. Upon entering the room, you observe two balloons suspended from the ceiling. You notice that
instead of hanging straight down vertically, the balloons seems to be repelling each other. You can
conclusively say ...
a. both balloons have a negative charge.
b. both balloons have a positive charge.
c. one balloon is charge positively and the other negatively.
d. both balloons are charged with the same type of charge.
4. Balloons X , Y and Z are suspended from strings as shown at the right. Negatively charged
balloon X attracts balloon Y and balloon Y attracts balloon Z. Balloon Z ____.
List all that apply.
a. may be positively charged
b. may be negatively charged
c. may be neutral
d. must be positively charged
e. must be negatively charged
f. must be neutral
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Electrostatic Mock Test 4
Polarisation
1. A rubber balloon possess a positive charge. If brought near and touched to the door of a wooden
cabinet, it sticks to the door. This does not occur with an uncharged balloon. These two observations
can lead one to conclude that the wall is _____.
a. electrically neutral
b. negatively charged
c. a conductor
d. lacking electrons
2. Which of the diagrams below best represents the charge distribution on a metal sphere when a
positively charged plastic tube is placed nearby?
3. True or False:
When an object becomes polarized, it acquires a charge and becomes a charged object.
4. A negatively charged balloon is brought near a neutral conducting sphere as shown below. As it
approaches, charge within the sphere will distribute itself in a very specific manner. Which one of
the diagrams below properly depicts the distribution of charge in the sphere?
5. TRUE or FALSE:
An object that becomes grounded gains neutrons during the grounding process.
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Electrostatic Mock Test 5
Electric Fields
1. Suppose that the sphere of a Van de Graaff generator gathers a charge. Then the motor is turned
off and the sphere is allowed to reach electrostatic equilibrium. The charge ___.
a. resides both on its surface and throughout its volume
b. resides mostly inside the sphere and only emerges outside when touched
c. resides only on the surface of the sphere
2. Describe the electric field strength at the six labelled locations of the
irregularly shaped, charged object at the right.
Use the phrases
"zero," ..........................................
"relatively weak," ...............................
"moderate," and ................................
“relatively strong" ..............................
as your descriptions, and write the correct letter behind the phrase.
3. Consider the diagram of the thumb tack shown at the right. Suppose
that the thumb tack becomes positively charged. Draw the electric field
lines surrounding the thumb tack.
4. Diagram the electric field lines for the following configuration of two
objects. Place arrows on your field lines.
5. A favourite physics demonstration used with the Van de Graaff generator involves slowly
approaching the dome holding a paper clip stretched towards the device. Why does the
demonstrator not become toast when approaching the machine with the blunt edge of the paper clip
protruding forward?
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Electrostatic Solutions 1 Charges
1. Answer: E
Electrons are negatively charged and protons are positively charged. The neutrons do not have a
charge.
2. Answer: False
Positively charged objects have electrons; they simply possess more protons than electrons.
3. Answer: False
Negatively charged objects have protons; it's just their number of electrons is greater than their
number of protons.
4. Answer: False
Electrically neutral atoms simply possess the same number of electrons as protons. This gives the
objects a balance of both type of charge.
5. Answer:
"I'll bet you 20 bucks you're wrong." or "No Way!" or ...
Electrons are not positively charged. Positively charged objects have an excess of protons (which
are positively charged).
6. Answers: a. Gain electrons AND b. Lose electrons
Protons are tightly bound in the nucleus and can be neither gained nor loss. So any change in the
charge of an atom is due to changes in its electron count. If a neutral atom gains electrons, then it
will become negatively charged. If a neutral atom loses electrons, then it becomes positively
charged.
7. Answer: C
Electric forces are repulsive for objects of like charge and attractive between objects of the opposite
type of charge or between charged objects and neutral objects.
8. Answer: B
Both C and Y are charged with excess + charge. Having the same type of charge, they will repel.
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Electrostatic Solutions 2 Conductors & Insulators
1. Answer: A is rubber and B is copper.
Sphere A shown a non-uniform distribution of excess charge; so sphere A must be made of an
insulating material such as rubber. Sphere B shows a uniform distribution of excess charge; one
would reason that it is made of a conductor such as copper.
2. Answer; B, C and E
Aluminium and silver are metals, making them good conductors. The human body is a fairly good
conductor. When wet, its an even better conductor.
3. Answer: F
A and B are characteristic of positive and negative objects. As for C, both insulators and conductors
can be charged. As for D, this has nothing to do with the conductive properties of materials. As for
E, neutrons are located in the nucleus and are "out of the way" of mobile electrons.
4. Answer: C
Rule out A since atoms are not capable of moving within solid spheres. Rule out B since protons are
not capable of moving in electrostatic demos. C is the proper explanation since the negative
electrons are attracted to the region of positive charge. The electrons migrate towards the left side of
the sphere until there is a uniform distribution of positive charge.
5. As fuel is pumped from the tanker car to a reservoir, charge can quickly build up as the fluid
flows through the hoses. This static charge can create sparks capable of igniting the fuel. By
connecting the body of the tanker car to the ground, the static charge can be transferred to the
ground. A metal wire is used since metals are conductive and allow charge to flow through them.
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Electrostatic Solutions 3 Charge Interactions
1. Answer: A
X is charged and Y is neutral. Charged and neutral objects always attract each other.
2. Answers : C and D are -; E and F are +
It's best to start on the right side of the table. Observing the E-F repulsion is enough to conclude that
both E and F MUST be charged with like charge. Since F and A attract, the charge on F is +; and
thus the charge on E must also be +. The C-D repulsion is sufficient evidence to conclude that both
C and D MUST be charged. Since D and E attract, D must have the opposite charge of E. E has
been declared as +, so D MUST be -. If C has like charge as D, it must be - also.
3. Answer: D
Observing a repulsive interaction is sufficient evidence to conclude that both balloons are charged.
However, further testing or additional information would be required to determine the type of
charge the balloons have.
4. Answers: A, B and C
Y is observed to attract a negatively charged object (balloon X). So Y could be either positively
charged or neutral. Y attracts Z. If Y were neutral (and we don't know for sure that it is), then Z
would attract Y if it were either + or -. So A and B are two possible answers. But Y could be
positively charged. And if Y were positively charged, the Y-Z attraction would be observed if Z
were neutral. So choice C is also possible.
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Electrostatics Solutions 4 Polarisation
1. Answer: A
Observing the positively charged balloon stick to the wall is
evidence that the wall is either neutral or charged negatively. Once
the second observation is made, one can conclude that the wall is
neutral. If it were charged, then the wall and the uncharged balloon
should attract.
2. Answer: D
In each case, the tube (in pink) is charged. Its charge should polarize
the metal sphere. This is not shown in A; so A can be ruled out. In
B, C and D the sphere is polarized. But in B and C, the diagram
shows the separation of charge in a manner that would indicate an attraction between like charges.
On the other hand, D shows that the negative charge on the sphere is attracted to the positive tube.
3. Answer: False
When an object becomes polarized, its centre of positive charge becomes separated from its centre
of negative charge. Overall, there are just as many positive charges as negative charges; the object
has a balance of charges and is therefore neutral.
4. Answer: C
Since the balloon is charged negatively, electrons in the sphere will be repelled and move from the
left side to the right side of the sphere. As a result, the left side of the sphere will have an excess of
positive charge (since it lost electrons) and the right side will have an excess of negative charge
(since it gained the electrons).
5. Answer: False
Neutrons are positioned in the nucleus of an atom. And like protons, neutrons are never transferred
in electrostatic experiments. They are bound in the nucleus and cannot escape by ordinary
electrostatic methods.
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Electrostatic Solutions 5 Electric Fields
1:
Answer: C
When a "closed" conductor becomes charged, the excess of charge accumulates on the outer surface
of the conductor. Since the generator has been turned off, there is no source of charge inside of it.
All the charge resides on the outside of the dome.
2.
Answers:
A, F are relatively strong since they're the most pointed locations on the conductor's surface.
B, E are relatively weak since they're at the least curved (most flat) locations on the conductor's
surface.
C is of moderate strength since it is at a location with some curvature but not an extreme amount.
D is 0 since it is at a location under the surface of the conductor; electric fields are zero inside of
conductors.
3.
Answer:
4.
Answer:
5. Answer:
An uncoiled paper clip becomes an object with a blunt edge with extreme curvature at its tip. This
extreme curvature creates strong electric fields around its surface. The strength of the electric field
is great enough to ionize the air between the paper clip and the Van de Graaff dome. This provides a
conducting path from the dome to the clip. Charge that normally accumulates on the dome now
flows through the ionized air and is grounded through the demonstrator. Rather than experiencing a
sudden discharge of large quantities of charge, there is a gradual non-harmful (so he claims) flow of
charge off the dome.
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Electrodynamics Mock Test 1
Electric Circuit
Which of the following statements are true about an electric circuit? List all that apply.
1. Electrons are the mobile charge carriers in an electric circuit.
2. The path of charge flow from the + to the - terminal of the circuit can consist of
nonconductive material.
3. In an electric circuit of an automobile, the 12-Volt car battery is sometimes referred to as the
internal circuit because it is located inside of the hood of the car.
4. Charge is supplied with energy in the internal circuit and the energy is transformed into
other forms in the external circuit.
5. Charge is consumed as it moves through the energy-transforming devices of the external
circuit. For instance, the amount of charge entering a light bulb in a second is less than that
which exits the light bulb in a second.
6. A battery is used to power a flashlight circuit. When the battery no longer works, it is
because it has run out of charge.
7. The location on an electric circuit where the charge possesses the greatest amount of electric
potential energy is the + terminal of the battery.
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Electrodynamics Mock Test 2
Electric Potential
Which of the following statements are true about an electric potential or electric potential
difference? List all that apply.
a) Electric potential can be expressed in units of volts.
b) Electric potential can also be expressed in units of Joules.
c) The electric potential of a charge at a given location provides a measure of the rate at which
charge flows past that point.
d) Work must be done on a + charge to move it against (i.e., in the opposite direction of) an
electric field.
e) As a + charge moves in the same direction as an electric field, it gains electric potential.
f) The electric potential difference between two points is simply the difference in potential
energy possessed by charge between those two points.
g) If a unit of charge has a high electric potential at any given location, then that charge
possesses a large amount of electric potential energy at that location.
h) The + terminal of a battery is a location with a higher electric potential than the - terminal of
a battery.
i) Charge flowing through a battery will experience a gain in electric potential.
j) A 6-Volt battery would provide 12 Joules of energy to 2 Coulombs of charge as it is moved
from the - to the + terminal.
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Electrodynamics Mock Test 3
Electric Current
Which of the following statements are true about electric current? List all that apply.
a) Electric current is measured in units of Amperes.
b) Electric current and drift speed are synonymous terms.
c) Electric current is defined as the number of Coulombs of charge which move past a point on
a circuit.
d) Electric current is equal to the number of Coulombs of charge which move past a point on a
circuit per unit of time.
e) Electric current provides a measure of how fast charge moves between two points on a
circuit.
f) The electric current diminishes in value as charge progresses to locations further and further
from the + terminal of the battery.
g) The electric current in a circuit will increase as the electric potential impressed across a
circuit is increased.
h) The electric current in a circuit will triple in value as the electric potential impressed across a
circuit is increased by a factor of three.
i) Suppose a miniature light bulb is connected to a battery in a circuit. A light bulb with a
greater resistance will have a greater current.
j) Wider conducting wires are capable of carrying larger currents.
k) If one starts getting technical about the meaning of electric current, one could argue that
electric current is not something that flows past a point on a circuit, but rather something that
exists to a given measure at a point on a circuit.
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Electrodynamics Mock Test 4
Electric Resistance
Which of the following statements are true about an electric resistance? List all that apply.
a) The resistance of an electric circuit is a measure of the overall amount of hindrance to the
flow of charge through the circuit.
b) A large resistance value indicates that the charge is encountering a relatively large amount of
difficulty in moving through the circuit.
c) The unit of resistance is the ampere.
d) A 5-ohm resistor would allow a current of 0.5 Amperes when 2.5 Volts is impressed across
it.
e) A 10-ohm resistor would allow a current of 2 Amperes when 5 Volts is impressed across it.
f) The resistance of a conducting wire will increase as the length of the wire is increased.
g) The resistance of a conducting wire will increase as the cross-sectional area of the wire is
increased.
h) Increasing the resistance of an electric circuit will cause the current in the circuit to increase.
i) A threefold increase in the resistance of an electric circuit will result in a threefold decrease
in the electric current.
j) A miniature light bulb with a specific resistance is connected to a 1.5-Volt battery to form a
circuit. If it were connected to a 6-Volt battery instead, its resistance would increase by a
factor of 4.
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Electrodynamics Mock Test 5
Electric Power
Which of the following statements are true about electric power and electric potential energy?
List all that apply.
a) Power is the amount of energy used by an electrical appliance.
b) Power is the rate at which energy is used by an electric circuit.
c) A kiloWatt•hour is a unit of electric power.
d) A Joule/second is a unit of power.
e) A 60-Watt light bulb would consume 30 Joules of electrical energy in 2 seconds.
f) A 120-Watt light bulb would consume 1200 Joules of electrical energy in 6 seconds.
g) A charge moving through an electric circuit would gain electric potential energy in the
internal circuit and lose electric potential energy in the external circuit.
h) Charge has the greatest amount of electric potential energy at the - terminal of the battery.
i) If a 60-Watt light bulb is placed in a 120-Volt circuit, then the current in the light bulb is 2
Amps.
j) Consider two light bulbs with different power ratings. A 60-Watt light bulb has a greater
resistance than a 100-Watt light bulb.
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Electrodynamics Answers 1: Electrical Circuits
1. TRUE - Physicists often speak of conventional current as the direction that positive charge
moves through a circuit. This is based on the convention that the direction of the electric field is the
direction that a + test charge would be accelerated. In reality, the carrier of electric charge in an
electric circuit is the electron.
2. FALSE - For charge to flow through an external circuit, the pathway must consist of conductive
materials. The presence of a nonconductor would inhibit charge flow and low the current to zero.
3. FALSE - The internal circuit is the portion of the circuit inside the battery, located between the terminal and the + terminal. Whether the battery is inside the hood or not has nothing to do with it.
If you were to place your battery on top of your hood, it would still be the internal circuit.
4. TRUE - The battery is the internal circuit; it is the place where charge acquires its energy. The
external circuit consists of wires, light bulbs, resistors, etc. In the external circuit, charge has its
electrical energy transformed into other forms as it passes through the elements of the external
circuit.
5. FALSE - Charge is neither created nor destroyed, and as such, the amount of charge which enters
a light bulb in a second is equal to the amount of charge which exits the light bulb in a second. This
quantity (charge per second) is the current and it is everywhere the same in a circuit.
6. FALSE - Batteries produce energy through a exothermic chemical reaction. When a battery no
longer works, the ability of its chemical reaction to produce products and energy has become
limited by the depletion of reaction and the build up of products. It has not run out of charge; it has
run of out chemical reactants.
7. TRUE - Know this one! The + terminal is the location of high energy in an electric circuit.
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Electrodynamics Answers 2: Electric potential
a. TRUE - Electric potential, also known as voltage, is measured in units of volts.
b. FALSE - The electric potential at a given location in a circuit is defined the electric potential
energy per charge at the location. Its units would be energy units per charge units - a Joule per
Coulomb (not simply a Joule).
c. FALSE - The rate at which charge flows past a point is the current. Electric potential is the
potential energy per charge at a given location.
d. TRUE - By convention, an electric field is the direction which a positive test charge would be
pushed or pulled. If a positive charge is moved against an electric field, then work must be done
upon the charge to overcome the opposing effect of the field.
e. FALSE - A positive charge moving in the direction of an electric field is moving without any
external help. Such a charge is analogous to a bicycle moving downhill; the bicyclist would not
have to pedal. In such instances, there is a loss in electric potential energy, and thus a loss in electric
potential.
f. FALSE - Close, but not correct. The difference in electric potential between any two points is
simply the different in electric potential energy per charge between those two points. Using a
gravitational analogy, gravitational potential is the difference in gravitational potential energy per
mass between any two points. Gravitational potential energy is dependent upon the amount of mass
present at a location (m•g•h); the more mass present at a location , the more gravitational potential
energy. In contrast, gravitational potential reduces the importance of mass by defining itself as the
potential energy per kilogram of mass (PE / m). By so doing, gravitational potential is now only
location dependent - depending only upon the value of g at a given location and the height above
some zero reference level. In the same manner, electric potential energy at a given location is
charge-dependent. The more charge present at a location, the more repulsive (or attractive) effects
and the greater the potential energy. But electric potential makes the amount of charge unimportant
since it is the electric potential energy per charge. Now electric potential is location dependent dependent for instance on the location in a circuit and not upon the amount of charge flowing past
that location in a second.
g. TRUE - Electric potential is the potential energy per charge at a given location. The more electric
potential which a unit of charge has at a given location, the more electric potential energy that the
charge has.
h. TRUE - In the battery, the positive terminal is the location of high energy and high potential. The
negative terminal is the location of low energy and low potential.
i. TRUE - In the battery, a charge is moved from a location of low energy to a location of high
energy. The charge would gain electric potential energy and as such, it would also gain electric
potential.
j. TRUE - A 6-Volt battery supplies every Coulomb of charge with 6 Joules of energy. The energy
per charge ratio is 6 Joules per Coulomb. Thus, 2 Coulombs of charge would gain 12 Joules of
energy.
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Electrodynamics Answers 3: Electric Current
a. TRUE - Electric current is the rate at which charge flows past a point on a circuit. It is measured
in Coulombs per second, also known as an Ampere or an "Amp."
b. FALSE - No! Current refers to how many Coulombs of charge pass a cross-sectional area in a
wire in a second of time. Drift speed refers to the distance that a mobile charge carrier travels in a
unit of time. One quantity - current - has to do with how many? and the other quantity - drift speed has to do with how far?
c. FALSE - Current is a rate quantity much like velocity or power is a rate quantity. There is a per
time basis to it. Current is defined as the Coulombs of charge which pass a point on a circuit per
second of time.
d. TRUE - Yes! This is the definition of current - a definition which ought to be committed to
memory.
e. FALSE - See the explanation to part b above.
f. FALSE - Charge is marching around a circuit at the same rate everywhere within the circuit. The
number of Coulombs which exit the battery at the + terminal in a second is equal to the number of
Coulombs which enter the battery at the - terminal in a second. Charge is not created; charge is not
destroyed; and charge does not accumulate at a location in a circuit. Charge simply marches
together around the loop of a circuit. The quantity which is lost and gained is energy. Work is done
on the charge as it passes through the battery, thus pumping the charge up to a high energy. And the
charge subsequently does work upon the elements of the external circuit, transforming its electric
potential energy to other useful forms (light, sound, mechanical, thermal, etc.).
g. TRUE - A higher electric potential impressed across the two terminals of a battery will cause the
rate of charge flow (i.e., current) to increase. This is consistent with the V = I•R equation.
h. TRUE - Consistent with V = I•R, one could say that the current is directly proportional to the
voltage. A tripling of the voltage (while R is held constant) would cause a tripling of the current.
i. FALSE - A light bulb with a greater resistance will offer more hindrance to the flow of charge
through it and as such lead to less current. Since I = V / R, the quantities current and resistance are
inversely proportional.
j. TRUE - A wider wire has a greater cross-sectional area and thus offers less resistance. As such,
wider wires allow a greater current or flow rate.
k. TRUE - Technically speaking, current does not flow or move. Current is a quantity which is
measured at a location and is based upon the rate at which charge flows. Teachers and textbooks
often get sloppy with their language and say that the current flows. In reality, it is the charge that
does the moving; the current is simply measured at a location to reveal the rate at which charge
flows past that location.
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Electrodynamics Answers 4: Resistance
a. TRUE - Yes! Remember this as the definition of resistance.
b. TRUE - Resistance refers to the amount of hindrance (resistance) to the flow of charge. The
more hindrance which charge encounters, the more resistance.
c. FALSE - The unit of resistance is the ohm. Ampere or Amps is the unit of current.
d. TRUE - The resistance of a resistor is the V/I ratio at that location. A 5-ohm resistor would have
a 5:1 ratio of voltage to current. This is a true statement since (2.5 Volt) / (0.5 A) is equal to 5.0
Volt/Amp.
e. FALSE - The resistance of a resistor is the V/I ratio at that location. A 10-ohm resistor would
have a 10:1 ratio of voltage to current. This is a false statement since (5 Volt) / (2 A) is not equal to
10 Volt/Amp.
f. TRUE - The resistance of a wire is mathematically related to the resistively of the material, the
length of the wire and the cross-sectional area of the wire. Longer wires have a greater resistance.
g. FALSE - The resistance of a wire is mathematically related to the resistively of the material, the
length of the wire and the cross-sectional area of the wire. Wider wires have a lower resistance.
h. FALSE - More resistance would cause less current.
i. TRUE - In accordance with the equation I = V / R, current is inversely proportional to the
resistance. Tripling the resistance will cause the current to decrease by a factor of three.
j. FALSE - The resistance of a light bulb is an intrinsic property which depends upon the material
and dimensions (length and diameter) of the light bulb filament. If the same light bulb is connected
to a battery of greater potential, only the current at the bulb location will be modified.
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Electrodynamics Answers 5: Electrical Power
a. FALSE - Power is a rate quantity; it is the rate at which energy is used by an electrical appliance.
b. TRUE - Yes! Know this definition.
c. FALSE - A kiloWatt is a unit of power. An hour is a unit of time. Power is energy per time. So
when power is multiplied by time, the result is energy. A kiloWatt•hour is a unit of energy.
d. TRUE - Power is the rate at which energy is used by an electrical appliance. As such, power is
measure in energy per time units - Joules per second.
e. FALSE - Power is the energy per time ratio. A 60-Watt bulb would consume 60 Joules of energy
in 1 second, 120 Joules of energy in 2 seconds, and 30 Joules of energy in 0.5 seconds.
f. FALSE - Power is the energy per time ratio. A 120-Watt bulb would consume 120 Joules of
energy in 1 second, 720 Joules of energy in 6 seconds, and 1200 Joules of energy in 10 seconds.
g. TRUE - This is how an electric circuit work. The internal circuit supplies electrical energy to the
charge and the electrical energy is converted to other forms of energy in the external circuit.
h. FALSE - The - terminal is the location of lowest energy in an electric circuit. the location of
highest energy is the + terminal.
i. FALSE - Power is related to voltage and current by the equation P = I•V. So a 60-Watt bulb
would allow a current of 0.5 Amps if wired into a 120-Volt circuit.
j. TRUE - A 60-Watt light bulb and a 100-Watt light bulb have different resistance values, which in
turn effects the current at the light bulb location. The bulb with the greatest resistance has the lower
current. So which bulb - high power or low power - has the greatest resistance? One must consider
the expression for power which includes both the current (I) and the resistance (R) since the choice
of bulb will effect both variables. The equation P = I2•R is of outmost importance here. In the
equation, the I is of double the importance since it is the square term in the equation. So the bulb
with the greatest I is the bulb with the greatest power. The 100-Watt bulb has the greatest current;
and therefore it must have the lowest resistance. The 60-Watt bulb has the greatest resistance.
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