PHY132 – Review for Mid-Term Test
“Examinations are formidable even to the best
prepared, for the greatest fool may ask more
than the wisest man can answer.”
Charles Caleb Colton, English writer (17801832)
“I was thrown out of college for cheating on the
metaphysics exam; I looked into the soul of the
boy sitting next to me.”
Woody Allen, American actor & director (1935- )
PHY132S Lecture 13 - EM Lecture 5 - Slide 1
PHY132 Mid-Term Test
– General Comments

6:10 - 7:30 PM, Tuesday, February 24

It is mandatory that you go to the room
assigned to your tutorial group.

Test information and room assignments are on
the PHY132 home page via the Portal

You should have no communication device
(phone, pager, etc.) within your reach or field
of vision during the test.
PHY132S Lecture 13 - EM Lecture 5 - Slide 2
PHY132 Mid-Term Test
–Format


Format - similar to PHY131 Mid-Term Test
9 equally weighted multiple-choice questions
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A long-answer section for 37 marks
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Each question has 4 or 5 possible answers.
Each correct answer will be awarded 7 marks.
Blank, incorrect, and multiple answers get 0.
Two questions: one short, one multi-part
Will be graded in detail with part marks awarded
as appropriate only if you show your work.
The test will be marked out of 100 points.
PHY132S Lecture 13 - EM Lecture 5 - Slide 3
PHY132 Mid-Term Test
– Don’t Forget ...



Your student card.
A non-programmable calculator without
text storage and communication capability.
A single original, handwritten 22 × 28 cm
sheet of paper on which you have written
anything you wish on both sides.


Numerical constants will be provided.
One or more dark-black, soft-lead 2B or
2HB pencils and an eraser.
PHY132S Lecture 13 - EM Lecture 5 - Slide 4
PHY132 Mid-Term Test
– Some Advice


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A good aid-sheet is well organized, easy to
read, and contains all the major equations
from the assigned sections from the reading.
Copies of detailed specific problem solutions
are unlikely to help.
Be ready to think; get a good night’s sleep
tomorrow night.
PHY132S Lecture 13 - EM Lecture 5 - Slide 5
PHY132 Mid-Term Test
– Material Covered 1
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All material from Lectures 1 through 13
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Waves & Oscillations and Electromagnetism
This includes
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All assigned sections from the textbook, whether
they were discussed in the lectures or not
Lecture notes - sidescreen and tablet
All figures and diagrams discussed
MasteringPhysics questions
Practicals
PHY132S Lecture 13 - EM Lecture 5 - Slide 6
PHY132 Mid-Term Test
– Material Covered 2

The test includes conceptual and
calculation questions

The test does NOT include


Supplementary material not discussed in class
Integration (BUT you should know the integral
and derivative relationships that we’ve
covered)
PHY132S Lecture 13 - EM Lecture 5 - Slide 7
Physics Drop-In Centre

Location: MP200, right above main lobby

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Help desk is in small room at North end of Centre
Extended Hours: 10AM - 5PM, Feb. 9-12 and
23-26, closed Reading Week
Can just drop in (no need for appointment)
Check the schedule at:
http://www.physics.utoronto.ca
/undergraduate/dic/dic-schedule.htm
PHY132S Lecture 13 - EM Lecture 5 - Slide 8
The Waves Section:
8 Classes in 10 Slides



The text and our classes often introduced
material in a spiral fashion: the various
concepts were introduced in pieces.
Here I try to make the review of that
material more linear.
Therefore the review will not always be in
the order in which the material was
discussed.
PHY132S Lecture 13 - EM Lecture 5 - Slide 9
Traveling Waves

Two views:
• We are at some fixed place and watch the
wave go by (history graph)
• We view the wave at a fixed time (snapshot
graph)
 For a sinusoidal wave we can combine the two
views analytically: D ( x, t )  A sin( kx  t  0 )
• Minus sign: wave traveling to the right
• Plus sign: wave traveling to the left
 Mechanical Waves:
• Travel through the medium
• Wave speed relative to that medium
PHY132S Lecture 13 - EM Lecture 5 - Slide 10
Traveling Sinusoidal Waves
 Source: some sort of Simple Harmonic Motion
 Source stationary relative to the medium:
fwave = fsource
 f = v (just d / t = v )
• v a property of the medium
 Source moving relative to the medium:
Doppler Effect: fwave  fsource
All Traveling Waves
Power
2
Intensity 
 Amplitude
Area
PHY132S Lecture 13 - EM Lecture 5 - Slide 11
Reflection (incident wave traveling
from left to right)
 Medium to right has as a smaller wave speed
than medium to the left: reflected wave phase
shifted by 
• This includes a “fixed end”
 Medium to right greater speed than medium to
the left: reflected wave not phase shifted
• This includes a “free end”
PHY132S Lecture 13 - EM Lecture 5 - Slide 12
Superposition
 Standing Waves: Superposition of incident and
reflected waves
 Interference: Superposition of two waves with
equal wavelengths:
• Constructive: two waves in phase
• Destructive: two waves out of phase by 
 Beats: Superposition of two waves with nearly
equal frequencies:
• A wave of frequency = the average frequency
• Modulated by an amplitude that varies
sinusoidally as ½ the difference in the
frequencies
PHY132S Lecture 13 - EM Lecture 5 - Slide 13
Superposition – more
 The double slit
• Maxima: difference in path length m 
• Minima: difference in path length (m + ½) 
 Decrease distance d between slits: spread out the
interference pattern, and vice versa
 “Diffraction” Grating: an array of N slits
 Reflection Grating: an array of N reflecting
surfaces
 Diffraction
• Only qualitative
• Decrease size of aperture: increase the spread
PHY132S Lecture 13 - EM Lecture 5 - Slide 14
Superposition – even more!
 Interferometers, especially the Michelson
Interferometer
Refraction
 Wave Model: sin( 1 )  sin(  2 )
v1
 For light:
v2
n1 sin(1 )  n2 sin( 2 )
0
n
sin(

)

n
sin(
90
)
 Total Internal Reflection: 1
C
2
PHY132S Lecture 13 - EM Lecture 5 - Slide 15
Ray Model




Travel in straight lines
Can cross (superposition)
Travels until it interacts with matter
An object is a source of light rays going in all
directions
 The eye sees by focusing a diverging bundle of
rays
PHY132S Lecture 13 - EM Lecture 5 - Slide 16
Reflection
 incident = reflected
 Plane mirror: forms a virtual image
PHY132S Lecture 13 - EM Lecture 5 - Slide 17
Lenses & Curved Mirrors
Thins Lens / Thin Mirror Approximation
 Parallel rays are brought to a focus at the focal point
 Distance from lens/mirror to the focal point is the
focal length f
1 1 1
 For both ray tracing gives:  
f s s'
 Converging lens / Concave mirror: f > 0
Diverging lens / Convex mirror: f < 0
 s’ > 0: real image
s’ < 0 : virtual image
h'
s'
 Lateral Magnification: m    
h
s
PHY132S Lecture 13 - EM Lecture 5 - Slide 18
Multiple Thin Lenses / Thin Mirrors
 The image of the first is the object for the second
Thick Lens
 The image of the first surface is the object for
the second surface
Dispersion
 For some media, wave speed depends on the
wave frequency
 Often we talk about the wavelength instead of
the frequency
PHY132S Lecture 13 - EM Lecture 5 - Slide 19
PHY132 Mid-Term Test
– Electromagnetism Review

Chapter 26 - all sections

Chapter 27 - §27.1, 27.2, 27.5


in §27.3, we used Equation 27.14 (page 825)

in §27.4, we used Equation 27.26 (page 832)
Chapter 29 - §29.1, 29.2, 29.3
PHY132S Lecture 13 - EM Lecture 5 - Slide 20
Electric Forces - Coulomb’s Law
F1 on 2
Two like
charges
r
q
F2 on 1
q1
F1on 2
Opposite
charges
F1 on 2
q
2
F2 on 1
2
q1
q1 q2
1 q1 q2
 F2 on 1  K 2 
2
r
4o r


F1on 2  F2 on 1
PHY132S Lecture 13 - EM Lecture 5 - Slide 21
Electric Fields
The electric field describes
the electric force on a test
charge at any point in space.


Fon q' ( x, y, z)
E( x, y, z) 
q'
1 q

, away from q
2
4o r
PHY132S Lecture 13 - EM Lecture 5 - Slide 22
Electric Field Lines (for a Dipole)
Tangent to field
line is in the
direction of the
electric field at
that point.
Electric
dipole moment:

p( x, y, z)  qs,
from - to 
PHY132S Lecture 13 - EM Lecture 5 - Slide 23
Parallel Plate Capacitor - Uniform
Electric Field & Potential Energy


Q
E capacitor 

,
o o A
from  to  plate
Uelec   Welec (i  f )
 qE s
Uelec  Uo  qEs
PHY132S Lecture 13 - EM Lecture 5 - Slide 24
Electric Potential Energy of a
System of Two Point Charges
Uelec
1 q1q2

4o r
PHY132S Lecture 13 - EM Lecture 5 - Slide 25
Good Luck!
PHY132S Lecture 13 - EM Lecture 5 - Slide 26