Download EM, Waves, Modern

Regents Physics
Wells
Electricity & Magnetism , Waves & Optics,
Modern & Nuclear
HW30-HW35
- Electricity
HW36-HW41
- Waves and Optics
HW42
- Modern
Physics HW #30
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HW30a – Questions below.
1.) What did Milikan’s oil-drop experiment reveal about the nature of electric charge? Explain fully what it
means.
2.) A typical lightning bolt has about -10 C of charge. How many excess electrons are in a typical lightning bolt?
3.) How are conductors different from insulators?
4.) Metals, such as copper and silver can be charged by induction, while plastic materials cannot. Explain why.
5.) When a conductor is charged by induction, how does the surface charge on the conductor compare to the
charge on the object inducing the surface charge. Explain your answer and use diagrams to support it.
6.) A negatively charged balloon has -3.5 µC of charge. How many excess electrons are on the balloon, show
equation and work.
7.) If a suspended object is attracted to another object that is charged, can you conclude that the suspended
object is DEFINTIELY charged? Explain your answer.
8.) Explain from an atomic point of view why charge is usually transferred by electrons
9.) Because of a higher moisture content, air is a better conductor of charge in the summer than in the winter.
Would you expect the shocks from static electricity to be more severe in the summer or winter, explain your
answer.
10.) Which effect proved more conclusively that an object is charged, attraction or repulsion from another
object? Explain.
11.) A metal sphere insulated from ground with a charge of + 5 µC is touched to another identical sphere with a
charge of -3 µC on it.
(a) Draw a sketch of the spheres before touching and label their charges, and then a sketch of the spheres
touching with the total net charge, then a third sketch of the spheres when they are separated again with their
resulting charges
(b) How much charge is transferred, and how is the charge transferred (describe how the motion of charge
happens)
(c) how many electrons are transferred and from where to where.
12.) In a lab experiment a student charges three objects and reports the following values as the charge on these
object 
8x10-19 C
2.72x10-18 C
1.84 x 10-18 C
Which one of these values is flawed and why, explain and support your answer mathematically.
13) A lightweight sphere hangs by an insulating thread. A student wishes to determine if the sphere is neutral or
electrostatically charged. She has a negatively charged hard rubber rod and a positively charged glass rod. She
does not touch the sphere with the rods, but runs tests by bringing them near the sphere one at a time.
a) Describe the test result that would prove that the sphere is neutral.
b) Describe the test result that would prove that the sphere is positively charged.
PAGE 2 of 2
14) Two electrically neutral metal spheres, A and B, on insulating stands
are placed in contact with each other. A negatively charged rod is
brought near, but does not touch the spheres, as shown in the diagram
below. How are the spheres now charged?
(1) A is positive and B is positive.
(2) A is positive and B is negative.
(3) A is negative and B is positive.
(4) A is negative and B is negative.
15) When a neutral metal sphere is charged by contact with a positively charged glass rod, the sphere
(1) loses electrons (3) loses protons
(2) gains electrons (4) gains protons
16) An electroscope is a device with a metal knob, a metal stem, and freely hanging metal leaves used to detect
charges. The diagram below shows a positively charged leaf electroscope. As a positively charged glass rod is
brought near the knob of the electroscope, explain what happens to the leaves of the electroscope and the
cause of this result.
HW30b – Castle Learning problems online
HW30A – ANSWERS - 1) Charge is quantized, comes in packs, 2) 6.25x1019 e, 3) charge flows easily in conductors
while the opposite in insulators, 4) need charges to flow during induction and that only happens in conductors,
plastic is an insulator, 5) The surface charge on the conductor is always opposite of the charge used to perform
the induction since in essence the like charges are being removed from the nearby object leaving behind
opposite type of charge, 6) 2.19x1013 e, 7) since both neutral objects and opposite charged object attract, you
cannot conclude this, 8) electrons are loosely bound and easy to move, 9) more severe shocks in winter since
charge can build up and does not ‘leak off’ into the moister air, 10) repulsion, see #7, 11a) net charge +2uC
leaving each with +1uc in the end, b) looking at the 5uC charge, it went from +5uc to +1uc (got less positive) so
must have gained negatives, -4uC was added to it from the other sphere, c) converting, 2.5x1013 –e’s
transferred, 12) divide each by 1.6x10-19 to see if it is an integer, based on Millikan’s findings, shows that only
the last one is wrong (11.5 e). 13a) bring each rod near one at a time, if it attracts both its neutral, b) bring the +
rod near and if it repels both are +, 14) choice 2, 15) choice 1, 16) The leaves spread apart even more. There are
still a lot of – charges in the + sphere, When the + rod is brought near, negative charges in the electroscope are
drawn up towards the top, leaving the leaves even more + than they were originally so they repel further.
Physics HW #31
PAGE 1 of 1
HW31A
1.) What is the magnitude of the electrostatic force between two electrons separated by 1.00 x 10 –8 m?
2.) What is magnitude of the charge on two identical spheres that exert a force on each other of 0.3 N when they are 70 cm
apart? STATE YOUR ANSWER IN units of µC AND ALSO in scientific notation in units of C
3.) Three charges are located on a straight line 10 mm from each other. The charges have magnitudes of +7e, -3e and -2e
respectively (meaning the – 3e charge is in the middle of the other two).
(a) Draw a sketch of the three charges and draw force vectors to represent the force on the -2e charge.
(b) What is the magnitude of the force on the -2e charge?
4.) 3 charges are located on an x-axis. A +3 µC charge is located at x=0, a -2 µC charge is located at x= -20 cm, and a +4.5 µC
charge is located at x=35 cm. Determine the force magnitude and direction on the charge at x=0.
5.) Given the following materials: (2 metal spheres mounted on glass rods, 1 piece of rabbit fur, 1 rubber rod) Explain and
use pictures to show how you can make the two spheres charged by only allowing them to touch each other and not having
other objects touch them. Show the sign of the charge on each sphere in your diagrams.
6.) What are some similarities and differences between the electric force and the gravitational force?
7.) The electric force between two charged objects is increased by a factor of 2 while the charge remains constant. By what
factor has the distance between the charges changed, show how you arrive at your answer?
8.) If the charge on each of two objects is doubled and the objects are moved three times closer than they were originally,
by what factor does the electric force increase by? (show work)
9.) Two objects 1 cm apart each have four elementary charges on them. If two of the charges are removed from one object
and placed on the other object, by what factor does the electric force change by? (show work or explain)
10.) The moon is bound to the earth by the force of gravity.
(a) Determine the force of gravity between the moon and the earth
(b) How much charge would have to be placed on objects the same distance apart as the earth and the moon in order the
create and electric force that is the same as the gravitational force found above.
11.) Two identical metal spheres insulated from the ground have charges of +8 mC and -4 mC. Describe in terms of electron
flow what happens when they are brought into contact (BE SURE TO USE THE ACTUAL NUMBER OF ELECTRONS AND STATE
WHAT IS HAPPENING TO THEM. Note: there is no such thing as a positive electron)
12.) The distance between an electron and a proton is varied. Which pair of graphs best represents the relationship
between gravitational force, Fg, and distance, r, and the relationship between electrostatic force, Fe, and distance, r, for
these particles?
HW31B – Castle Learning (online)
Answers – 1) 2.3x10-12 N, 2) 4x10-6, 4µC, 3) 5.75x10-24 N (F1=8.06x10-24, F2=1.38x10-23), 4) 2.34 N directed towards –x axis
(F1=1.35, F2=0.99), 5) this is induction, see your notes, 6) both inverse squared laws, Fe is stronger and can be both
attractive and repulsive while gravity can only be attractive, 7) increase by √0.5 x, 8) 36 x, 9) 0.75 x,
10) FG=1.99x1020 N, 5.71x1013 C, 11) +8mc turns into +2mc so becomes less +, gains -6mC charge, this converts to 3.75x1016
electrons move from -4 to +8 charge, 12) both are inverse squared, choice 1
HW32
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HW 32A Questions
1.) Electrons are about 5.3 x 10-11 m away from protons on average. What is the magnitude and direction of the electric
field that the proton creates at this radius away from it?
2.) An uniform electric field of 1.4 x 104 N/C is directed along the positive x-axis. (a) What is the magnitude and direction of
the electric force on an electron in this field (b) What is the magnitude and direction of the electric force on a proton in this
field.
3.) A +10 nC charge creates and electric field of 5x103 N/C at what location away from the charge?
4.) An electron moving through an electric field in outer space experiences an acceleration of 2.3 x 10 3 m/s2. (a) Find the
electric force acting on the electron (b) What is the strength of the electric field?
5.) A proton is placed at rest in an external uniform field of 470 N/C. Calculate (a) the force acting on the proton, (b) the
acceleration of the proton as it moves through the field, (c) the speed after 42 ns. (b) repeat the exercise for an electron.
6.) A point charge is shown below. Draw a single electric field vector to represent the electric field created at point P away
from the charge
P ●
+
7.) Two equal but opposite sign point charges are shown. In diagram A, draw two single electric field vectors at point P and
label them E1 and E2 to represent the electric field created from each charge independently. Then in diagram B, draw a
single electric field vector to represent the total resultant electric field from both charges at point P
Diagram A
Diagram B
P ●
+
P ●
1
+
2
1
2
8.) For the examples shown below, sketch enough electric field lines to be representative of the electric field at any location
around the charges (like we did in class)
(b)
(a)
+4
+1
-3
+2
PAGE 2 of 2
9.) The object shown is given a net negative charge. Draw a sketch of the distribution of the
excess negative charge on the object
10.) When electric field lines are being drawn, what determines the number of lines originating from a charge? What
determines whether the lines originate from or terminate on a charge?
11.) When defining the electric field, why must the magnitude of the test charge be very small?
12.) The figure shows the field lines for two point charges. (a) What is the sign of the
charges (b) Determine the ratio of qA / qB (explain answers or show work)
13.) An experiment is conducted where various charges are placed in an electric field and the forces on those charges is
measured. The data is collected in a table shown below. Make a graph of electric force vs. charge for the above data, draw
a best fit line, label the graph and axis with units and use the graph to determine the magnitude of the electric field.
Charge ( C )
1
1.5
2
2.5
3
3.5
Electric
Force (N)
10.5
15
21.6
25
31.5
39.9
HW 32B – Castle Learning
32A Answers: 1) 5.12x1011 N/C away from the charge, 2a) 2.24x10-15 N directed in –x, b) 2.24x10-15 N directed
in +x, 3) 0.13 m, 4a) 2.1x10-27 N b) 1.3x10-8 N/C, 5a) 7.52x10-17 N, b) 4.5x1010 m/s2, c) 1890 m/s, d) 7.52x10-17 N, 8.25x1013
m/s2, 3.5x106 m/s, 6) single arrow up and right, 7) A) two single arrows, one up right the other down right, b) resultant of
part A, arrow pointing right, 8) field lines, see notes, 9) also in notes, no charge inside, excess on the corners, 10) +out, - in,
11) in notes and textbook, 12) A+, B-, 18:8, 13) slope = 11.42 N/C
Physics HW #33
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HW 33A Questions –
1.) What is electric current and what is the unit for it
2.) Each of the wires shown here are made of copper. Assuming each piece is the same temperature, which has the
greatest resistance and which has the least resistance, explain your answer
A
B
C
D
3.) What is the difference between direct current and alternating current
4.) What factors affect the resistance of a conductor
5.) A proton starts from rest and gains 8.35 x 10–14 joule of kinetic energy as it accelerates between points A and B in an
electric field.
a) What is the final speed of the proton?
b) Calculate the potential difference between points A and B in the electric field.
6.) A 1.4 m long piece of wire has a cross sectional radius of 2 mm. Find the resistance of the wire if it was made of
(a) copper
(b) silver
7.) 8 electrons are grouped together and moved by a potential of 1.5 V. How much energy, in joules and electronvolts can
these electrons provide.
8.) In a particular TV tube, the beam current is 20µA. How long does it take for 2 x 1014 electrons to strike the screen?
9.) A proton is moved 10 cm against a 5x103 N/C electric field. (a) Determine the force acting on the proton, (b) Determine
the work done moving the proton, (c) Determine the potential difference the proton is moved through.
10.) An electric meter is attached to a 1.0714 m long wire to measure its resistance. It the wire has a cross sectional area 3
x 10-5 m2 and a resistance of 2 mΩ, (a) what is the wire made out of and (b) what is the radius of the wire.
11.) The charge that passes through the filament of a certain light bulb in 2.5 sec is 2.7C (a) What is the current in the bulb,
(b) How many electrons pass through the filament of the light bulb in a time of 1 min.
12.) A potential difference of 10 V produces a current of 0.3 A in a 4 m long piece of copper wire. (a) What is the resistance
of the wire. (b) What is the cross sectional area of the wire
13.) A person notices a mild shock if the current along a path through the thumb and index finger exceeds 80µA. Determine
the maximum allowable potential difference without shock across the thumb and index finger for the following: (a) dry-skin
with a resistance of 4 x 105 Ω (b) wet-skin with a resistance of 2 x 103 Ω
14) A 3.50-meter length of wire with a cross-sectional area of 3.14 x10–6 meter2 is at 20° Celsius. The current in the wire is
24.0 amperes when connected to a 1.50-volt source of potential difference.
a) Determine the resistance of the wire.
b) Calculate the resistivity of the wire
PAGE 2 OF 2
15) A constant potential difference is applied across a variable resistor held at constant temperature. Which
graph best represents the relationship between the resistance of the variable resistor and the current through
it?
16) An experiment was performed using various lengths of a conductor of uniform cross-sectional area. The
resistance of each length was measured and the data recorded in the
table below.
Using the information in the data table, construct a graph on the grid
provided following the directions below.
a) Plot the data points for resistance versus length, label axis and title
graph accordingly.
b) Draw the best-fit line.
c) Calculate the slope of the best-fit line.
HW33B – Castle Learning
Answers: 1-4) Concepts from notes.
5a) 1x107 m/s, b) 521875V, 6a) 0.001916 Ω, b) 0.001771 Ω, 7) 1.92x10-18 J, 12 eV, 8) 1.6 sec, 9a) 8x10-16 N,
b) 8x10-17 J, c) 500 V, 10) 5.6x10-8 Ω·m therefore its tungsten, b) 0.00309 m, 11a) 1.08 A, b) 4.05x1020
12a) 33.33 Ω, b) 2.06x10-9 m2, 13a) 32 v, b) 0.16 V , 14a) 0.0625 Ω, 5.6x10-8 Ω·m, 15) Choice 1, inverse
Physics HW #34
PAGE 1 OF 2
HW 34A Questions – Part 1
1.) A 5 Ω, 10 Ω, and 15 Ω resistor are connected in series, explain answers or show work.
(a) Which resistor has the most current in it (b) Which resistor has the largest potential drop across it (c) What is total
equivalent resistance
2.) Answer question #2 if the resistors were connected in parallel
3.) A length of wire can be considered to be an infinite number of tiny resistors connected in series. The wire is cut into five
equal pieces. If each piece has a resistance of 0.15 Ω what was the resistance of the original length of wire?
4.) Two resistors are wired in series. In another circuit, the same two resistors are wired in parallel. In which circuit is the
equivalent resistance higher, explain.
5.) Draw a circuit diagram containing a 12V battery, and a 2 Ω resistor in parallel with two 4 Ω resistors that are in series
with each other. Add a switch to control the whole circuit. Add a voltmeter to measure to voltage of the 2 Ω resistor and
an ammeter to measure the current through the 4 Ω resistors.
6.) An 8 Ω resistor and two 6 Ω resistors are connected in series with a battery. The potential difference across the 8 Ω
resistor is measured as 12 V. Find the potential difference across the battery, draw the circuit.
7.) A 9 Ω and a 6 Ω resistor are connected in parallel to a battery, and the current in the 9 Ω resistor is found to be 0.25 A.
Find the potential difference across the battery, draw the circuit.
8.) An 18 Ω, 9 Ω and 6 Ω resistor are connected in parallel with an emf source. The current in the 9 Ω resistor is measured
to be 4 A. (a) Calculate the equivalent resistance of the three resistors in the circuit. (b) Find the potential difference across
the emf source. (c) Find the current in the other resistors.
9) A 15-ohm resistor, R1, and a 30.-ohm resistor, R2, are to be connected in parallel between points A and B in a circuit
containing a 90.-volt battery.
a) Complete the diagram to show the two resistors connected in parallel between
points A and B. b) Determine the potential difference across resistor R1.
c) Calculate the current in resistor R1
10) Three lamps were connected in a circuit with a battery of constant potential. The current, potential difference, and
resistance for each lamp are listed in the data table below.
a) draw a circuit showing how the lamps and battery are connected.
b) What is the potential difference supplied by the battery?
c) Calculate the equivalent resistance of the circuit.
d) If lamp 3 is removed from the circuit, what would be the value of the potential difference across lamp 1 after lamp
3 is removed?
e) If lamp 3 is removed from the circuit, what would be the value of the current in lamp 2 after lamp 3 is removed?
PAGE 2 OF 2
11) In a physics lab, a student used the circuit shown to measure the current through and the potential drop across a
resistor of unknown resistance, R. The instructor told the student to use the switch to operate the circuit only long enough
to take each reading. The student’s measurements are recorded in the data table.
Using the information in the data table, construct a graph
on the grid in your answer booklet, following
the directions below.
a) Plot the data points for potential
drop versus current and label axis
and title appropriately.
b) Draw the line or curve of best fit.
c) Calculate the slope of the line or
curve of best fit.
HW34B – Castle Learning
ANSWERS: 1) all same, more V goes with more R, 30 ohm, 2) least R gets most I, all same, using reciprocals R total equals
2.73 ohms, 3) in series R=0.75 ohm. 4) more R in series,
5) schematic drawing, using proper symbols, resistors and batteries should be arranged as shown below:
6) 30 V, 7) 2.25 V, 8a) 3 ohm, b) 36V, c) 2A, 6A
R
9a) Draw this
using proper symbols, b) 90 V, c) 6A
V
R
R
R
R
10a) Since V is same in all they must have been in parallel, draw them in parallel, b) 40.1 V, c) 47.7 ohms, d) same as before
40.1 V, e) same as before 0.11 A
11) Graphing, linear best fit, slope = 32 ohms.
Physics HW #35
PAGE 1 OF 2
HW35A – Questions
1.) Which physical quantity is correctly paired with its unit?
(1) power and watt•seconds
(2) energy and newton•seconds
(3) electric current and amperes/coulomb (4) electric potential difference and joules/coulomb
2.) What does the power rating on a light bulb describe?
3.) How many joules of energy are dissipated by a 50 W bulb in 2 seconds
4.) How many joules of energy are in a 2 kilowatt-hours
5.) An X-ray tube used for cancer therapy operates at 4 MV (mega volt) with a beam current of 25 mA (milli-Amp) striking a
metal target. Calculate the power of the beam
6.) A 11 W fluorescent lamp is designed to produce the same illumination as a conventional 40 W bulb.
(a) How much energy does the 11 W lamp save during 100 hrs of use compared to the 40W lamp?
(b) If electrical energy costs $0.08 / kW-hr, how much money is saved in 100 hrs?
7.) An electric car is designed to run on a bank of batteries with a total potential difference of 12 V and a total energy
storage of 2 x 107 J.
(a) If the electric motor runs with a power of 8 kW, what is the current delivered to the motor?
(b) If the car moves at a steady speed of 20 m/s, how far will the car travel before if is “out of juice”?
8.) A 120 V potential is applied to an electric heater rated at 1200 W, a toaster rated at 1100 W, and an electric grill rated at
1500 W. The three appliances are connected in parallel across a 120 V emf source. Draw the circuit.
(a) Find the current in each appliance
(b) Find the resistance of each appliance
(c) Is a 30 A circuit breaker sufficient in this situation, explain?
(d) If the devices were connected in series, what would happen to their power ratings, explain.
9) Which graph best represents the relationship between the power expended by a resistor that obeys Ohm’s Law and the
potential difference applied to the resistor?
10) A small electric motor is used to lift a 0.50-kilogram mass at constant speed. If the mass is lifted a vertical distance of 1.5
meters in 5.0 seconds, the average power developed by the motor is
11) A device operating at a potential difference of1.5 volts draws a current of 0.20 ampere. How much energy is used by the
device in 60. seconds?
12) Which graph represents the relationship between the power and the current in a resistor that obeys Ohm’s Law?
13) Two bulbs are connected in parallel as shown
PAGE 2 OF 2
/\/\/\
/\/\/\
If one of these bulbs was removed, how would the following quantities be
affected: State you answer as INCREASE, DECREASE or REMAIN THE SAME and
give a brief explanation why.
(a) Voltage of remaining bulbs, (b) Current of remaining bulbs, (c) Power usage of
remaining bulbs, (d) Brightness of remaining bulbs, (e) Total resistance of circuit,
(f) Total current flowing in circuit
14) Answer each question again if instead the bulbs were initially connected in series and one was removed
15.) A light bulb is rated at 100 W for a 120 V source of potential. It is connected as shown. X is simply a labeled point in
the circuit and does not affect the results otherwise.
(a) How much current is flowing through the
bulb in this setup?
/\/\/\
120
V
100 W
(b) What is the resistance of the light bulb
(note: this remains constant)
X
A second identical bulb labeled 100 W is added to the circuit at point X. (Note that the bulbs are no longer 100 W bulbs;
the bulbs need to receive 120 V to be 100 W bulbs. Since they are hooked in series, they do not each get the 120 V needed
to be a 100 W bulb so the 100 W writing becomes irrelevant and only their resistance stays the same)
(c) Given that the resistance in found in part b is the resistance of each bulb, determine the voltage and current that each
bulb will have when they are hooked in series
(d) Using the results from part c, determine the new power ratings of the bulbs in this series configuration
(e) Would adding the second bulb make the first bulb brighter, dimmer or unaffected, explain briefly
16) A variable resistor was connected to a battery. As the resistance was adjusted, the current and power in the circuit were
determined. The data are recorded in the table below.
Using the information in the data table, construct a line graph on the grid provided
a) Draw the best-fit line.
b) Using your graph, determine the
power delivered to the circuit at a
current of 3.5 amperes.
c) Calculate the slope of the graph.
d) What is the physical significance of
the slope of the graph?
HW35B – Castle Learning
Answers: 1) 4 since V=W/q, 2) rate of energy use (J/s), 3) 100 J, 4) 7.2x106 J, 5) 1x105 W, 6a) 2.9 kW-hr or 1.04x107 J b)
$0.232, 7a) 666.7 A, b) 50000 m, 8a) 10A, 9.2A, 12.5A, b) 12 Ω, 13 Ω, 9.6 Ω, c) No, I tot too big, 9) 4, 10) 1.47 W, 11) 18 J, 12)
4, 13) a-d) all same, e) more R, f) less I, 14) a-d) all more, e) less R, f) more I, 15a) 0.83A, b) 144.58 Ω, c) V=60.7 V each,
I=0.42A each, d) 25.5 W, e) dimmer, more total R = less I, 16) graph linear, slope=3 W/A, slope represents P/I which is
voltage.
HW36A Questions
HW36B – No Castle Learning for this assignments
PAGE 1 of 1
READ CHAPTER 12-3 and 12-4 and Answer the questions below.
1.) Given that all Electromagnetic Waves travel at the speed of light, determine the wavelength of the following
EM waves (A) 880 MHz radio wave (B) 6x10 8 MHz light ray (C) 3x1012 MHz X-ray
2.) If the amplitude of a sound is increased by a factor of four, by how much does the energy of the wave
change
3.) How do transverse and longitudinal waves differ, don’t simply define each, draw specific attention to
differences.
4.) The disturbance shown below is traveling to the right, what direction are the particles of the medium traveling
and what type of wave is this.
5.) Give an example of a mechanical wave, how is this different from an electromagnetic wave.
6.) In your own words, explain what constructive and destructive interference is, do not simply copy definitions
from the book.
7.) Two waves, each of amplitude 2m interfere at a point with complete destructive interference, what is the
displacement of the resultant wave.
8.) What happens to a wave pulse when it reflects off a fixed boundary
9.) How will the displacement of a wave at a trough, compare to the displacement at a crest.
ANSWERS – read the text, the answers are in there.
HW37A – Pendulums Questions
HW37B – No Castle Learning for this HW
Page 1 of 2
1.) A pinball machine uses a spring that is compressed 4 cm to launch a ball. If the spring constant is 13 N/m,
what is the force on the ball at the moment the spring is released.
2.) A trapeze artist swings in simple harmonic motion with a period of 3.8 s. Calculate the length of the cables
supporting the trapeze.
3.) Calculate the period and freq uency of a 3.5 m long pendulum at the following locations
(a) North pole, g = 9.832 m/s2
(b) Chicago, g = 9.803 m/s2
(c) Indonesia, g = 9.782 m/s2
4.) When a 25 g mass is attached to a certain spring, it makes 20 complete vibrations in 4 s. What is the spring
constant of the spring.
5.) A 125 N object vibrates with a period of 3.56 sec when hanging from a spring. What is the spring constant of
the spring
6.) A 0.75 kg mass attached to a vertical spring stretches the spring 0.30 m. (a) What is the spring constant of
the spring? (b) What is the resulting period of oscillation if the mass is set into simple harmonic motion?
7.) A child swings on a playground swing. How many times does the child swing through the equilibrium position
during the course of a single period of motion
8.) How is the period of a simple harmonic vibration related to its frequency
9.) How much does the period of a simple pendulum change when the length is doubled? How much does it
change when the mass is doubled?
10.) A pendulum is placed on an airplane and set into vibratory motion. How will the period change as the plane
increases altitude, explain answer.
11.) Will the period of a mass spring system be the same on the earth and the moon, explain?
PAGE 2 of 2
12) In an experiment, a student measured the length and period
of a simple pendulum. The data table lists the length (L) of the
pendulum in meters and the square of the period (T 2) of the
pendulum in seconds2.
a) Using the information in the data table, construct a graph and
draw the best-fit straight line.
b) Using your graph, determine the time in seconds it would take
this pendulum to make one complete swing if it were 0.200 meter
long. [1]
c) The period of a pendulum is related to its length by the formula:
T 2 = ( 4 pi2 / g ) • L where g represents the acceleration due to
gravity. Explain how the graph you have drawn could be used to
calculate the value of g, then perform this calculation
ANSWERS – 1) 0.52 N, 2) 3.59 m, 3a) 3.788 s, 0.267 Hz, b) 3.754 s, 0.2664 Hz, c) 3.758 s, 0.2661 Hz, 4) 24.67
N/m, 5) 36.69 N/m, 6a) 24.53 N/m, b) 1.1 sec, 7) 2x, 8) 1/f inverse, 9) rad 2 x more, no change, 10) more T, 11)
Yes, 12a) linear, b) pick point such as T2=0.8 so T=0.9 sec, c) pick points and plug in 9.9 m/s 2
HW38A - Waves Questions
HW38B – Return of Castle Learning – YES.
PAGE 1 of 2
1.) Radio waves travel at the speed of light. An amateur radio system can receive radio signals at frequencies
between the range of 8 MHz and 1.2 MHz. What is the corresponding range of wavelengths this system can
receive?
2.) The graphs below represent different measurements of the same wave. Use these graphs to answer the
questions that follow
I.)
2
0
-2
0
0.01
0.02
0.03
0.04
0.05
60
80
100
Tim e (sec)
II.)
2
0
-2
0
20
40
Distance (m )
(a) Determine the wavelength of the wave
(b) Determine the period of the wave
(c) Determine the frequency of the wave
(d) Determine the speed of the wave
3.) In a stretch spring, several coils are pinched together and release. What type of wave results
4.) The distance a wave travels in one period of time is referred to as what?
5.) A rope is shook up and down three times in one seconds. What is the period and frequency of the resulting
wave
PAGE 2 of 2
6.) Why do sound waves need a medium to travel through
7.) A 256 Hz tuning fork and a 512 Hz tuning fork are struck simultaneously. Which has a larger speed, which
has a larger wavelength, explain
8.) The wave shown below has a frequency of 25 Hz. Determine the waves (A) amplitude (B) wavelength (C)
Period (D) Speed
18 cm
10 cm
9.) Use the principle of superposition to draw the resultant of the waves shown. Show your sketch below each
wave
1a
1b
2a
3a
2b
3b
10.) Under what conditions can two waves interfere and make a larger resultant wave
11) In which direction will particle A move in the next instant of time?
(1) up
(2) down
(3) left
(4) right
HW38B – Castle Learning Online
ANSWERS – 1) 37.5 – 250 m, 2a) 40 m, 0.02 s, 50 Hz, 2000 m/s, 3) longitudinal, 4) 1 λ, 5) 0.3 sec, 3 Hz, 6) its
mechanical, 7) same speed, 256 hz more λ inverse related to f, 8a) 9 cm, b) 20 cm, c) 0.04 s, d) 500 cm/s, 91)big up, big down, big up, 9-2) all flat, 9-3) medium up, medium down, medium up, 10) displacement on same
side, constructive, 11) choice 2
HW39A – Sound and Diffraction Questions
PAGE 1 of 2
1.)
The diagram above represent the sound waves emanating from a moving sound source.
(a) Which direction is the source moving
(b) How does the frequency on the right side compare to the frequency on the left side of the diagram
2.) A vibrating tuning fork is brought near a second tuning fork at rest of equal frequency, what will happen,
explain.
3.) If the wavelength of a sound is reduced by a factor of 2, what happens to its speed and what happens to its
frequency.
4.) Under what conditions will resonance occur
5.) Soldiers are usually required to march in step, but need to break their march when crossing a bridge, explain
the possibly danger of marching in step across a bridge.
6.) Two light waves interfere constructively, (a) what is the necessary condition for path length difference to
achieve this result. (b) what condition would produce destructive interference
7.) Interference in sound is recognized by differences in volume; how is interference in light recognized
8.) Draw 4 wavelets on the other side of the slit shown below to diagram the propagation of the wave as it
passes through the slit
9.) What is the wave term to describe what happens to the wave above
PAGE 2 of 2
10.) From problem #8, How would you have to change the wavelength of the incoming wave to make the
resultant wave passing through the slit resemble a beam with little spreading. Draw a sketch of the incoming
wavelets like those shown in problem #8 that would make this happen, explain your answer.
11.) The total length of a string is 2m and is fixed at both ends in each example. One end vibrates creating
standing wave patterns as shown below. Determine the wavelength of each wave shown
12.) Explain how the standing waves above are formed, using wave terms.
13) The sound wave produced by a trumpet has a frequency of 440 hertz. What is the distance between
successive compressions in this sound wave as it travels through air at STP?
14) A wave of constant wavelength diffracts as it passes through an opening in a barrier. As the size of the
opening is increased, the diffraction effects
(1) decrease
(2) increase
(3) remain the same
15) Increasing the amplitude of a sound wave produces a sound with
(1) lower speed
(2) higher pitch
(3) shorter wavelength
(4) greater loudness
16) Which wave phenomenon occurs when vibrations in one object cause vibrations in a second object?
17) The diagram represents shallow water waves of constant wavelength passing through two small openings, A
and B, in a barrier.
a) Is point P a point of constructive or destructive interference?
b) What physically would be observed as a result of this
interference?
c) What is the path difference at point P from sources A and B?
HW39B – Castle Learning Online
ANSWERS – 1a) right, b) more, 2) other fork vibrates also, resonance (sympathetic vibration), 3) const v, λ
down, f up, 4) when nat. freq = vibration freq., 5) constant stepping could match nat freq causing resonance, 6a)
any whole # of λ difference, b) any ½ λ # diff. 7) bright/dark spots, 8) half semicircular arcs (like #17 diagram),
9) diffraction, 10) need very small λ waves, 11) 4 m, 2m, 1.33 m, 1 m, 12) interference of incoming and reflected
wave, 13) 0.75 m, 14) 1, 15) 4. 16) resonance (sympathetic vibration), 17a) dest. b) still water, c) ½ λ
HW40A – Light and EM Waves Questions
PAGE 1 of 1
1.) An electromagnetic wave has a frequency of 7.57x10 14 Hz, what is the wavelength of this wave and what
‘classification’ of the electromagnetic spectrum does this wave belong.
2.) If you double the distance away from a light source, by what factor does the brightness of the source change
by
3.) A 560 nm wavelength light has the brightest impact on the human eye. What is the frequency of this light
wave? What specific ‘classification’ of the electromagnetic spectrum does this wave belong to?
4.) Describe the following examples as diffuse or specular reflection
(a) reflection of light from the surface of a lake on a calm day
(b) reflection of light from a plastic trash bag
(c) reflection of light from the lens of eyeglasses
(d) reflection of light from a carpet
_____________
_____________
_____________
_____________
5.) What band of the electromagnetic spectrum has (a) the lowest frequency (b) the shortest wavelength
6.) Which of the following EM waves has the highest frequency, explain
a) radio
b) ultraviolet
c) blue light
d) infrared radiation
7.) Which EM wave travels at a faster speed Gamma radiation, or Infrared radiation, explain
8.) Why do astronomers talk about observing distant galaxies as looking backward in time?
9.) What is the wavelength of radar signal with a frequency of 33 GHz
10.) How can you used two pairs of sunglasses to tell if they are polarized
11.) Draw a ray diagram to show the formation of an image in the plane mirror show below
12.) The diagram shows a light ray reflecting from a plane mirror. Determine the
angle of reflection for the light ray
HW40B – Castle Learning Online
ANSWERS – 1) violet, 3.96x10-7 m, 2) ¼ times, 3) green, 4) spec, diff, spec, diff, 5a) long radio, b) gamma, 6)
B, 7) same, 8) light takes long time to get here, 9) 0.009 m, 10) discussed in class / read textbook 11) ray
diagram as in notes, 12) 25 degrees
HW41 - Refraction
Page 1 OF 2
1.) For the following examples, state whether or not refraction will occur
(a)
(b)
(c)
(d)
(e)
(f)
_____
_____
_____
_____
_____
_____
light traveling from air into diamond at an angle of 30 degrees to the normal
light traveling from water into ice along the normal
light striking a metal surface
traveling from air into a glass of tea at an angle of 25 degree to the normal
light traveling from corn oil into glycerol
a sound wave moving from low temperature air into high temperature air.
2.) White light passes through a prism and is split into its component color frequencies (a) What is this process
called (b) Which color light bends more, red or green
3.) Does a light ray moving from one medium to another always bend towards the normal, explain?
4.) As light travels from a vacuum to glass, what happens to the waves frequency, speed and wavelength.
5.) What is the relationship between the velocity of light and the index of refraction
6.) Two colors of light, X and Y, are bent through a glass prism. X is bent more than Y. What can you conclude
of the speed change of light beam X, explain
7.) A friend throws a coin into a pool and you close your eyes and dive in towards the spot you saw it. When you
reach the bottom, will the actual coin be in front of or behind you in your current location. Draw a sketch of the
coin in the pool and the path of a light ray leaving the coin to show the image location.
8.) Is it possible to have total internal reflection for light incident from air to water, explain.
9.) A light ray travels between two medium in a variety of situations. Complete the table below for each
situation, show work
From (medium)
To (medium)
i
r
Flint glass
Crown glass
25.0
Air
14.5
9.8
Air
diamond
31.6
10.) a) Find the critical angle for light traveling from flint glass  water. b) If a light ray was incident on the
glass-water boundary at an angle of 50° from the normal would it refract into the water or undergo total internal
reflection?
11.) A ray of light enters to top of a glass of water at an angle of 36 with the normal. What is the angle
between the refracted ray and the normal.
12.) The angle of incidence and the angle of refraction for light going from air into a material with a higher index
of refraction are 63.5 degrees and 27.8 degrees respectively. What is this material
13.) A light ray travelling in corn oil approaches an air boundary at an angle of incidence of 46 degrees. Will it
undergo total internal reflection or refract into the air, justify your answer.
14.) The light ray shown is exiting a glass prism. Determine
the angle of refraction as the light ray exists the glass and
returns to the air, label it and shown both the reflected and
refracted ray at the glass-air interface
Page 2 OF 2
15.) A light ray travels from air to linseed oil (n=1.48) at an unknown angle of incidence 1. It strikes the
boundary and refracts at a refraction angle of 2 = 20 degrees as it enters the oil. The ray then continues on and
passes into the water and refracts at an unknown angle 3
(a) sketch the light ray and label all angles. (b) Determine the angles 1 and 2
Air
Linseed oil
Water
16) Based on the diagram shown:
The absolute index of refraction of medium X is
(1) less than 1.33
(2) greater than 1.33 and less than 1.52
(3) greater than 1.52 and less than 1.66
(4) equal to 1.66
EXPLAIN YOUR ANSWER.
17) A light ray traveling in air enters a second medium and its speed slows to 1.71 x 108 meters per second.
What is the absolute index of refraction of the second medium?
18) A periodic wave travels at speed
v through medium A. The wave
passes with all its energy into
medium B. The speed of the wave
through medium B is v/2. On the
diagram, draw the wave as it travels
through medium B.
HW41B – Castle Learning Online
ANSWERS 1) yes,no,no,yes,no,yes, 2) dispersion, more f=more bend, 3) depends on boundary condition MLA, LMT, 4) f
const, v less, λ less, 5) inverse, 6) more bending = more n = more slowing, 7) behind you, 8) no, must go moreless, 9) 27.49, glycerol, 12.5, 10a) 53.24°, b) since i < c it will refract, 11) 26.23°, 12) zircon, 13) total
reflection since θi actual > θc, 14) 68.17 degrees angles downwards away from normal, 15a) bends towards, then
away, b) 30.41°, 22.37°, 16) 4, 17) 1.75, 18) drawn wave should have ½ the wavelength (twice as many waves
in equal amount of distance), but be of the same amplitude.
HW42 – MODERN PHYSICS – ALL ON CASTLE LEARNING