Chapter 14, Sound
CHAPTER 14
14.1 Producing a Sound Wave 1. When a sine wave is used to represent a sound wave, the crest corresponds to: a. rarefaction. b. condensation. c. point where molecules vibr
Chapter 6, Momentum and Collisions
CHAPTER 6
6.1 Momentum and Impulse 1. A valid unit for momentum is which of the following? a. kgm/s2 b. kg/m2 c. kgm/s d. Nm 2. The dimensional equivalent of the qua
Chapter 5, Energy
CHAPTER 5
5.1 Work 1. The unit of work, joule, is dimensionally the same as: a. newton/second. b. newton/kilogram. c. newton-second. d. newton-meter. 2. Rupel pushes a box 5.00 m by
Chapter 12, The Laws of Thermodynamics
CHAPTER 12
12.1 Work in Thermodynamic Processes 1. The volume of an ideal gas changes from 0.40 to 0.55 m3 although its pressure remains constant at 50 000 Pa. W
Using Kirchhoffs rules
11
The variables for which you are solving are the
currents through the resistors.
You need as many independent equations as you
have variables to solve for.
If you are analyz
Voltmeters
16
A voltmeter is a device that measures the potential
difference across its inputs.
The voltmeter has very large resistance so that
very small amount of current would flow through it,
red
Clicker question: 2
13
Example: 3
14
Assume that R1=1.0 ,
R2=2.0 , E1=2.0V, and
E2=E3=4.0V.
a)
b)
Calculate the current through
each ideal battery.
Calculate Va-Vb.
Ammeters
15
An ammeter is a device that measures currents
passing through it.
To measure the current in the resistor, the current
must flow through the ammeter, so the ammeter has
to be connected in
Loop rule
6
The sum of the changes in potential around
any closed loop must equal zero.
The
potential drops passing through a resistor in the
direction of the current.
The potential increase going f
Lecture 23
2
Reading chapter 21-5 and 21-8.
Kirchhoffs
n Junction
rules
rule
n Loop rule
Ammeters
Voltmeters
Kirchhoffs rules
3
Complex circuits cannot be broken down into series
and parallel piece
Junction rule
4
The sum of the currents into a junction must
equal the sum of the currents out of the
junction.
I1 I 2 I 3 = 0
I1 = I 2 + I 3
Demo: 1
5
Conservation of current
Demonstration
of the cu
Open circuit
10
If there is a circuit where there is no closed path
through which electrons can flow, we call it a open
circuit.
When a switch is open, its an open circuit.
Clicker question: 1
11
Example: 1
12
Pacemakers designed for
long-term use commonly
employ a lithium-iodine
battery capable of supplying
Q=0.42Ah of charge.
a)
b)
How many coulombs of
charge can such a battery
supply?
If th
Equivalent resistance for resistors in series
10
For n resistors in series, the equivalent resistance is
n
Req = R1 + R2 + R3 + = Ri
i =1
Clicker question: 1
11
Lecture 22
2
Reading chapter 21-3 to 21-4.
Power
in electric circuits
Energy usage
Combined resistors
n Series
n Parallel
n Combination
circuits
Electric power
3
When a charge Q moves across a pote
Electric power delivered to a resistor
4
In a special case of a resistor, the power delivered
to the resistor while charges flow through it is given
by
2
V
P = IV = I 2 R =
R
expressed in three differ
Resistivity
18
Note the huge variations for .
The difference between insulators,
semiconductors, and conductors can
be clearly seen in their resistivities.
Copper is used commonly for
household wires.
Direction of current
8
The direction of current flow from the positive terminal
to the negative one was decided before it was
realized that electrons are negatively charged.
Current flows around a cir
Emf
6
A device that supplies electrical energy to a circuit is called a
source of emf.
Batteries (chemical energy to electrical energy)
Generators (mechanical energy to electrical energy)
The emf (E)
DC and AC
4
A closed path through which charge can flow,
returning to its starting point, is called an electric
circuit.
In a direct-current circuit (dc circuit), the current
always flows in the same
Example: 1
8
A 100W lightbulb is plugged into
a standard 120V outlet.
a)
How much does it cost per
month (31 days) to leave the
light turned on continuously?
Assume electrical energy costs
6 cents/kWh
Example: 1
7
a)
b)
c)
What is the equivalent
capacitance of three
capacitors?
What is the charge on C3?
What is the charge on C1?
C1
C2
V
C3
RC circuits
8
A circuit containing a resistor and capacitor
Pacemakers
11
When hearts natural pacemaker fails, you may need an electronic
pacemaker, which produces a regular voltage pulse that starts and controls
the frequency of the heartbeat.
The electrodes
Demo: 1
10
Relaxation oscillator (RC circuit)
A
capacitor, resistor, and 90V battery are hooked in
series with a neon bulb in parallel with the capacitor.
The capacitor charges to about 80V (the bre
Example: 1
4
The equivalent resistance between points
A and B of the resistors shown is
Req=26. An ideal battery with a
terminal voltage of V=12V is
connected to terminals A and B.
a)
b)
Find the valu