Lecture24 Exam 3 Review

8/3/2019 Lecture24 Exam 3 Review

1/13

Welcome to the Physics 24 Exam!

adapted from http://www.nearingzero.net(work022.jpg)

Dont forget to

pick up your testpreparationhomework.

With my chainsaw inmy left hand, myright hand is free for

the right hand rule!

Do you knowyour exam room?


2/13

Announcements

y Critically important! Lab make-up schedule:

Labs L02, L04, L06 will do their free Labor Daymakeup on Monday, November 28. Go to lab at yourregularly scheduled time and room. If you dont attend on

Nov. 28, you had better not miss any other labs.

Your lowest lab score is dropped. There are nomakeup labs (other than the Labor Day makeup describedabove).

The makeup lab is on the Monday after Thanksgiving break.You are going to forget about it!


3/13

Announcements

y Pick up test preparation homework from the back of thelecture hall. If I have revised it lately, I will tell you to getanother copy if you printed yours out earlier.

y Updated course grades will hopefully be available by 3:00pm, November 16. Grades spreadsheets will not be updatedover the weekends after exams.


4/13

Announcements

Remember Captain JackCrossproduct?

He may visit us on examday. You wouldnt wanthim to see you using yourleft hand for the right-

hand rule, would you?


5/13

Know the exam time!

Find your room ahead of time!

If at 5:00 on test day you are lost, go to 104 Physics and check the exam

room schedule, then go to the appropriate room and take the exam there.

Exam is from5:00-6:15 pm!

y Physics 24 TestRoom Assignments, Fall 2011:

Instructor Sections Room

Dr. Hagen K, L 295 ToomeyDr. Hale E, G 104 PhysicsDr. Hor J, M 227 FultonDr. Parris B, H 125 Butler-Carlton (Civil)Dr. Peacher D, F G-5 HSSDr. Schmitt A, C 120 Butler-Carlton (Civil)

4:30 and 5:30 Exams 202 PhysicsSpecial Needs Testing Center


6/13

Exam 3

Review

The problems in this lecture are the standard exam review lectureproblems and are not a guarantee of the exam content.

Please Look atPrior Tests!


7/13

Contents:

Biot-Savart law

fields and forces for current-carrying wires

motional emf

more motional emf

electromagnetic waves


8/13

A conductor consists of a circular loop of radius R and two longstraight sections as shown. The straight sections are radial.

The wire lies in the plane of the paper and carries current I.Determine the magnitude and direction of the magnetic field atthe center of the loop (assume the gap in the loop isnegligible).

IP


9/13

9

I1 = 6.0 A I2

cQ0.50 m 0.50 m

1.00 m

P

Two parallel conductors are separated by 1.0 m. The wire onthe left carries a current I1 = 6.0 A into the page. (a) What is

the direction and magnitude of I2 in order for the net magneticfield at pointP to be zero? (b) What is the magnitude anddirection of the net magnetic field at point Q. (c) If a thirdparallel wire is placed at Q and carries a current I3 = 2.0 A intothe page, what is the force per unit length on the wire at Q?


10/13

The curved part of a D-shaped conducting loop D is a half-circle of radius R. Current flows counterclockwise in the loop.

What is the magnetic field at the center of the half-circle dueto the infinitesimal piece of wire ds?

I

R

30

ds


11/13

A horizontal wire is free to slide on the vertical rails of aconducting frame as shown. The wire has mass per unit lengthQ and length L, and the resistance of the circuit is R. If auniform field is directed perpendicular to the frame and out ofthe page, what is the terminal speed of the wire as it fallsunder the force of gravity?

L

Bout

R


12/13

A rectangular telescoping conducting loop is being pulled open.Its height is H and its length is increasing at a rate L=L0+Et.The loop is in a uniform magnetic field as shown in thediagram. Calculate the magnitude and direction of the emfinduced in the loop.

BH

L


13/13

At what distance from a 100 W electromagnetic wave pointsource does Emax = 15.0 V/m? What is the average energydensity of the electromagnetic wave at that point?

A 100 mW laser beam is perfectly reflected directly back onitself by a mirror. Calculate the force the laser beam exerts onthe mirror.

2

0 max

1 PI S c E

2 A! ! I !

rad

I 2IP or

c c!

I

Q

2

2 max

0 max

0

B1 1u = E =

2 2

Lecture24 Exam 3 Review

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