15 mechanical waves
16 sound and hearing
21 Electric charge and electric field
Coulomb's law
where
and
Electric Field
wave power
Electric dipoles
Standing sound waves
inverse square law for intensity
Potential Energy of a pair of charges
final-initial, Ratio of Bob to Sally =
p=
n=
=
1kWh = 1 kW*3600s
C2/n m2
=
Volume of a sphere =
Volume of a cylinder =
m=
k=
m/s
olu e
(volume
Current Density
con
PHYS 2306 TuTh 9:30am
Prof. Satoru Emori
Doppler Effect
Standing Waves
2017 09/12
More info:
www.science.vt.edu/sowers
Announcements
Homework #2 will be due this Friday, 9/15.
Exam #1 will be on Frida
PHYS 2306 TuTh 9:30am
Prof. Satoru Emori
Potential and Field
Capacitance
2017 10/26
Practice Problem for 10/26:
Try this problem while you wait for the lecture to start.
a) Find the potential at x = x
PHYS 2306 TuTh 9:30am
Prof. Satoru Emori
Electric Potential
2017 10/19
Announcements
Exam #2 TOMORROW (Fri 10/20) at 5:30pm, 300 Whittemore
Chapters 25, 26, and 27 (Electric Charges/Forces, Electric F
PHYS 2306 TuTh 9:30am
Prof. Satoru Emori
Potential and Field
2017 10/24
Announcements
Thank you all 116 of you for taking Exam #2 as scheduled!
(I hope to make the scores available by the end of Thurs
Capacitance
Capacitors
Two separated conductors
charging transfer
s from one
to other
:
and
=
Capacitance:
units:
(farad)
Capacitance
depends only on geometric properties
separation
surface area
P
Practice Problem for 10/26:
Try this problem While you wait for the lecture to start.
a) Find the potential atx 2' X0 on the axis of the charged rod
shown in the figure below.
is/
W MMMMM ~\ nggdler S
PHYS 2306 TuTh 9:30am
Prof. Satoru Emori
Current and Resistance
2017 10/31
Practice Problem for 10/31:
Try this problem while you wait for the lecture to start.
(a) A battery with an emf of 60 V is
co
Practice Problem for 11/2:
Try this problem while you wait for the lecture to start.
[30.40] The electron beam inside a television picture tube is 0.40 mm
in diameter and carries a current of 50 uA. T
a. Figure 3 shows [\VO unequal point Charges. q and Q. ofopposite Sign. Charge Q has greater
nmgnitude than charge (1. In which of the regions X. Y. Z will there be a point at which the net
electric f
PHYS 2306 TuTh 9:30am
Prof. Satoru Emori
Current and Resistance
2017 11/02
Practice Problem for 11/2:
Try this problem while you wait for the lecture to start.
[30.40] The electron beam inside a telev
2.5 min
The potential energy between two point charges _ as
the charges move farther apart.
A. increases (a) @\> Water Molec/
B. remains constant
C. decreases Q9 9 _
D decreases for like charges,_ inc
PHYS 2306 TuTh 9:30am
Prof. Satoru Emori
Electric Field
2017 09/26
Announcements
Exam #1 will be graded this week
-Will try to get grades out by Thursday
Homework #4 will be due Friday, 9/29 at 11:59p
How to mathematically express an
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Gausss Law: general formula
For any closed surface enclosing total charge Qin, the
net electric flux through the surface is:
Ste/m cmx/WLTIW :
\ Q5 > 0 3(va Qw'l 04
CD : % ~+ . d : Qm all [6 oLoSMSMMQ
Electric field inside a metal
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Practice Problem for 10/31:
Try this problem While you wait for the lecture to start.
(a) A battery with an emf of 60 V is
1 M connected to the two capacitors shown
M \f i in the left figure. Afterwar
Potential, V
Potential, V
Constant potential: test charge does not roll
Position, x
If you raise the potential on one side.
Positive test charge rolls down
the slope of potential.
Position, x
ff?"
Current
&
Resistance
Current
Motion of
another.
from one region to
Requires constant applied
Net drift of charges
conventional current: direction
of +
=
unit: , ampere
Conventional Current
=
=
curren
Fundamentals
of
Circuits
Circuit Symbols
Measuring and
Ideally, meters shouldnt affect circuit
Ideal voltmeter:
Connected in parallel
=
=0
Ideal ammeter:
Connected in series
=0
=0
Basic Circuit T
Electric
Potential
Work & Energy Review
Conservative ,
=
=
cos
:
=
depends only on endpoints (path)
is reversible
0 if =
increases opposite direction of .
Conservation: W = =
+
=
+
Electric Potenti
Electric
Flux
Motivation
Calculating
difficult! Unless
Symmetric charge distribution
Previously:
Now:
?
Charge in the box?
Electric Flux,
Map
w/ test charge
flux: measure of the
flow of the electric
Traveling
Waves
Examples of Waves?
Types of (Mech.) Waves
wave: disturbance that propagates from one region to
another
mechanical wave: requires a medium
transverse mechanical wave: medium displaced t
Superposition
of
Waves
Interference
Defined: when 2+ waves overlap and combine
Principle of (linear) superposition
Total displacement of medium is the sum of
displacements due to individual waves.
i.e
Magnetic
Fields
Magnetism
Interactions between magnets described in terms of
poles.
magnetic charges opposites attract
Interactions due to magnetic field
.
Compass needles align w/
Direction of force
Oscillations
Definitions
oscillator: object whose motion
repeats in periodic fashion about an
equilibrium position
period: ; time to complete a cycle
frequency: ; # cycles / second
Units: Hertz, Hz or