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Welcome to Physics NYB Electricity and Magnetism
Gabe Rosenbaum
Contact via MIO
Office I-309
Office hours:
Mon 12-2, Wed 2-4, Thurs 2-4
Read the course outline!
This course is going to be
Fun
Interesting
Challenging (that means hard)
You are expected
Capacitance and Dielectrics
Capacitors
We have discussed capacitors as being two parallel plates with equal and opposite
charges.!
We have looked at the potential and electric field in the region between the plates. !
We will now consider the charge on ca
Magnetic Fields
Evidence of magnetism
Magnetic compasses used >3000 years ago.
Ancient Greeks knew about magnetism in early 800BC:
Ancient Chinese compass
Lodestone attacking paper clips
Today.
Why do we need something new?
+
+
We have also seen
We call t
Faradays Law
Faradays experiments
After discovering that currents can
produce magnetic fields people started
experimenting to see if magnetic fields
could produce currents.
Faraday was trying to produce a
current with a magnetic field but it
wasnt working
Direct Current Circuits
Conductors in an electric field
Conductors have a sea of mobile charges
These charges are free to move
If a conductor is placed in an E-field the charges
feel forces and move in the conductor.
This creates a field in the opposite d
INTEGRATIVE ACTIVITY EXERCISE
ELECTRICITY AND MAGNETISM (PHY-NYB)
In integral calculus, you learned about the process of integration. Specifically, you
conceptualized the integral as the limit of a Riemann Sum, and visualized this as
the signed area under
Electric Potential and Potential Energy
Work (a review)
Remember work?
The work done on an object by a force is:
In general the path and the force do not
have to be constant
Work (a review)
Find the work done on the cat by gravity.
h
work done on the cat
Inductance
Self-inductance
Wait a sec
If I close the switch there is a change in
the flux through the circuit.
There is therefore an induced current.
What direction is the induced current
caused by the increasing magnetic flux?
There are not actually two
Physics NYB - Super Problems - Review
1)A region of space has a uniform electric field in the positive x-direction with a
magnitude of 100V/m.
a.Sketch the equipotential lines.
b.An electron is placed at the origin at rest. What is its position and
veloci
Physics NYB - Magnetic Fields 1 - In class
1)What direction is the magnetic field at the point A? At point B?
!"
A!
B!
D
2)Find the vector E
= C
B
:
3)Find the vector A
= 2i + 3j
A
= 2i + 3j + 2k
B
Physics NYB - Magnetic Fields 1 - In class
4)Find the
Review Quiz
Q1
Rank in order from smallest to largest the electric field strengths at the
points shown near an infinite plane of positive charge.
A.
B.
C.
D.
d=e<b=c<a
a=b=c=d=e
b=c=d=e<a
a<b<c<d<e
Q2
The compass needle
A.
B.
C.
D.
rotates clockwise
rotat
Continuous Charge Distributions
This section of the course is what is covered in the integrative activity.
There is no new physics. Just some applications of what we have learned
(mostly just some extra math).
There is an assignment that you have have to
Physics NYB - Continuous Distributions 1 - In class
1)Find the total charge on each rod
!=1C/m
!2=2C/m
!1=1C/m
!1=3C/m
!1=-2C/m
0
2
!1=1C/m
4
!1=-1C/m
6
8
x [cm]
2)A charged rod lies on the x-axis between x=-L/2 and x=L/2. The rods linear
charge density i
Physics NYB - DC Circuits 2 - In class
1)Find the equivalent resistance
R2=8!"
R1=4!"
R4=1!"
R3=2!"
2)Find the current through each resistor if the potential difference between the
ends is 143V
Physics NYB - DC Circuits 2 - In class
3)Find the equivalent
Physics NYB - Capacitance 1 - In class
1)A parallel plate capacitor has an area of 2.00x10-4m2 and a plate separation of
1.00mm.
a.Find the capacitance.
b.If this capacitor is connected to a 9V battery how much charge is on the
capacitor?
2)Find the equiv
NYB - Prelab 1 - The Multimeter
Name:
Please read the Theory section of the lab manual, and fill out the following
exercise.
The graph below shows the plot of voltage (V / V) vs current (I / mA) for a given
conducting rod.
Graph 1: Voltage vs current
1
Vo
Physics NYB - Magnetic Fields 4 - In class
1)A long wire carries a 10A current from left to right. An electron, 10 cm away
from the wire is traveling to the right with a speed of 1.0x107m/s. What are the
magnitude and direction of the magnetic force felt
Physics NYB - Gausss Law - In class
1)Consider a uniform electric field (magnitude E) in the x-direction. Find the net
flux through the cube shown.
2)Find the electric flux passing through a sphere centered on a positive charge q.
Physics NYB - Gausss Law
Physics NYB - Electric Fields and Forces - In class
1)A 10cm rubber rod has a net charge of -3C. What is the linear charge density
of the rod? [ans: -30C/m]
2)A vinyl record (diameter 40cm) has a total charge of 10C on the top surface.
Find the amount of
Answers to the Physics NYB integrative activity
April 3, 2009
Abstract
This document only presents you with the final answer for the electric potential
and electric field for each of the continuous charge distributions in your integrative
activity. If you
Gausss Law
This is not Gausss Law, but it is cool
Symmetry
An object is said to be symmetric if a
geometric transformation does not cause
a physical change.
Symmetry of an infinitely long cylinder
None of these actions can change the
physics
Lets deduce t
NYB - Lab 1 - The Multimeter
Names:
Part 1: Circuit with a single resistor
Objective:
Conceptual Summary of Procedure:
EXPERIMENTAL DATA: Present your data in the table below. Make sure you
are using different resistors (R1 R2).
I(mA)
(target
values)
40
8
Physics NYB - Magnetic Fields 5 - In class
1)A 20cm bar with a resistance of 10 ohms is suspended from two rigid wires
and put into a 0.5T magnetic field as shown. The mass of the bar is 50g. What
does the potential of the power supply have to be for ther
Physics NYB - Continuous Distributions 2 - In class
1)Find the E-field at the point P due to the uniformly charged rod.
P
y
Q
L
2)Find the electric field due to a semicircular charged object that has two
uniform charge densities of equal magnitude and opp
NYB - Lab 2 - The Kirchhoffs Rules
Names:
Part 1: Kirchhoffs First and Second Rules
Objective:
Conceptual Summary of Procedure:
Draw the circuit on figure II - 3 and indicate the direction of the current through
each resistor with an arrow.
NYB - Lab 2 -
Physics NYB - Magnetic Fields 2 - In class
1)Find the field due to a long wire carrying a current I.
!"
Physics NYB - Magnetic Fields 2 - In class
2)Find the magnetic field due to a current loop at a point on the axis of the loop.
P!