Physics 21 Fall 2007
Solution to HW-19
31-9 (A) What is the reactance of an inductor with an inductance of 3.30 H at a frequency of 83.0 Hz? (B) What is the inductance of an inductor whose reactance is 13.0 at a frequency of 83.0 Hz? (C) What is t
Physics 21 Fall 2007
Solution to HW-4
Flux out of a Cube A point charge of magnitude Q is at the center of a cube with sides of length L. (A) What is the electric flux through each of the six faces of the cube? (B) What if L changes?
22.36 A long
Physics 21 Fall 2007
Solution to HW-5
Stopping the Proton An infinitely long line of charge has a linear charge density . A proton at distance r_0 from the line is moving directly toward the line with speed v. How close does the proton get to the l
Physics 21 Fall 2007
Solution to HW-11
27.63 A magnetic field exerts a torque on a round loop of wire carrying a current. What will be the torque on this loop (in terms of if the diameter of the loop is tripled? = x B. depends on area. If you
Physics 21 Fall 2007
Solution to HW-14
A Wire and a Compass You are looking straight down on a magnetic compass lying flat on a table. A wire is stretched horizontally under the table, parallel to and a short distance below the compass needle. The
Physics 21
Fall, 2012
Solution to HW-2
21-15 Three point charges are arranged on a line. Charge
q3 = +5.00 nC and is at the origin. Charge q2 = 3.00 nC
and is at x2 = 4.50 cm. Charge q1 is at x1 = 1.00 cm. What
is q1 (magnitude and sign) if the net force
Physics 21
Fall, 2012
Solution to HW-6
23-23 (a) An electron is to be accelerated from a velocity
of 2.50 106 m/s to a velocity of 8.00 106 m/s. Through
what potential dierence must the electron pass to accomplish this? (b) Through what potential dierence
Physics 21
Fall, 2012
Solution to HW-5
For surface S5 , the normal direction is in the +x direction,
so we integrate the component over the surface.
i
22-34 A cube has sides of length L = 0.330 m. It is placed
with one corner at the origin as shown in the
Physics 21
Fall, 2012
Solution to HW-3
A Test Charge. (Figure below) Consider three plastic
balls (A, B, and C), each carrying a uniformly distributed
charge equal to either +Q, Q or zero, and an uncharged
copper ball (D). A positive test charge (T) exper
Physics 21
Fall, 2012
Solution to HW-4
21-104 A thin disk with a circular hole at its center,
called an annulus, has inner radius R1 and outer radius
R2 . The disk has a uniform positive surface charge density on its surface. (a) Determine the total elect
Physics 21
Fall, 2014
Solution to HW-28
33-35 Unpolarized light of intensity 26.0 W/cm2 is incident on two polarizing lters. The axis of the rst lter is at
an angle of 24.8 counterclockwise from the vertical (viewed
in the direction the light is traveling
Previous Lecture
The potential of any point a is the work per unit charge to move a test charge from a reference point P to the point a:
Va = -
P
a
E dl.
The line integral is independent of the path.
p.
Today
V and E
Start Chapter 24: Capac
Physics 21 Fall 2007
Solution to HW-27
YF 34.99 When an object is placed at the proper distance to the left of a converging lens, the image is focused on a screen which is placed a distance of 30.4 cm to the right of the lens. A diverging lens is n
Physics 21 Fall 2007
Solution to HW-10
Electromagnetic velocity filter An ion source sends particles with velocity v along the +x axis. The particles encounter plates a distance d apart that generate a uniform electric field E in the +y direction.
Physics 21 Fall 2007
Solution to HW-15
28-39 A long, straight, cylindrical wire of radius R carries a current uniformly distributed over its cross section. At what location is the magnetic field produced by this current equal to half of its largest
Physics 21 Fall 2007
Solution to HW-16
29-6 A coil of radius r, containing N turns, is placed in a uniform magnetic field whose magnitude varies with time according to B=C_0 t + C_1 t^4. The coil is connected to a resistor R, and its plane is perpe
Physics 21 Fall 2007
Solution to HW-23
Transformers Consider the transformer ideal unless otherwise noted. (A) The primary coil of a transformer contains 100 turns; the secondary has 200 turns. The primary coil is connected to a size AA battery tha
29-45 In the circuit shown, the capacitor has capacitance C=20 F and is initially charged to 100 V with the polarity shown. The resistor R_0 has resistance 10 . At time t=0 the switch is closed. The small circuit is not connected in any way to the la
Physics 21 Fall 2007
Solution to HW-8
25.2 A silver wire 2.6 mm in diameter transfers a charge of 420 C in 80 minutes. Silver contains 5.8 x 1028 free electrons per m3. (A) What is the current in the wire? (B) What is the magnitude of the drift vel
Physics 21 Fall 2007
Solution to HW-9
26.64 Find the current throught the battery and through each battery in the circuit shown.
26.41 In the circuit shown, both capacitors are initially charged to V_1. (A) How long after closing the switch S will
Physics 21 Fall 2007
Solution to HW-6
Electric Fields and Equipotential Surfaces The dashed lines in the diagram represent equipotential lines drawn in 1 volt increments. (A) What is the work done by the electric force to move a 1 C charge from A to
Physics 21 Fall, 2007
Solution, Hour Exam #2
The graders for the problems were: 1 McGeehan, 2 Belony, 3 Sweeney, 4 Lyu, 5 Kanofsky For questions about the grading, see the grader by Nov. 20. Problem 1. For the following circuit, R = 5.0 , L = 40.0
Physics 21 Fall 2007
Solution to HW-26
K 23.13 A diamond is underwater. A light ray enters one face of the diamond, then travels at an angle of 31.0o with respect to the normal. What was the ray's angle of incidence on the diamond?
YF 34.57 A tele
Physics 21
Fall, 2014
Solution to HW-25
32-17 We can reasonably model a 60 W incandescent lightbulb as a sphere 5.2 cm in diameter. Typically, only about
5% of the energy goes to visible light; the rest goes largely
to nonvisible infrared radiation. a) Wh
Physics 21
Fall, 2014
Solution to HW-27
33.43 A ray of light is incident in air on a block of a transparent solid whose index of refraction is n. If n = 1.37, then
what is the largest angle of incidence a for which total internal reection will occur at th
Physics 21
Fall, 2014
Solution to Hour Exam #1
The graders for the problems were:
1. McMillen 2. Glueckstein 3. Cai 4. Veenhuizen.
For questions about the grading, see the grader by Oct. 24
Problem 1. In the circuit shown below the voltage E
of the batter
PHY21, Prof. I. Biaggio
Narrative due: Fri 09/02/2015 Final solution due: Fri 09/09/2015
Learning Homework 1 Narrative
In order to answer all the questions in this homework, one needs to
Look up the mass of a proton in order to calculate the gravitationa
Physics 21
Fall, 2014
Solution to HW-15
can treat B(x) as a known and solve for x:
0 I
R2
2 (R2 + x2 )3/2
0 I R 2
3/2
=N
R2 + x2
2 B(x)
B(x) = N
28-38 A closely wound, circular coil with radius 3.00 cm
has 850 turns. (a) What must the current in the coil
Physics 21
Fall, 2014
Solution to Hour Exam #2
The graders for the problems were:
1 Glueckstein, 2 Veenhuizen, 3 Teri Price, 4 Cai
For questions about the grading, see the grader by Nov. 21
Problem 1. For the following circuit:
(b) (3 pts.) Evaluate the p
Physics 21
Fall, 2014
Solution to HW-24
16.35 Two loudspeakers, A and B, are driven by the same
amplier and emit sinusoidal waves in phase. The frequency
of the waves emitted by each speaker is f = 693 Hz. You
are standing between the speakers, along the