Exam Wisdom

Life Without a Calculator

You don't have a calculator, so how do you work out a multiple-choice questions that have an answer in two or more significant figures? Do you need to do the tedious long division? NO. While the possible answers are calculated according to the correct value of Coulomb's constant, for example, the different choices are well separated numerically -so all you need to do is estimate an answer well enough to eliminate the other possible answers. Using a value of g=10 m/s^2, for instance, will always enable you distinguish the correct answer from the incorrect one, even though g is closer to 9.8 m/s^2. You never need to calculate a number to better than about 20% accuracy and usually much less precision is adequate. (At 20% you need to know the first significant digit, and have an estimate of the second digit). You will be safe using k = 9 x 10^9 N.M^2/C^2 throughout the exam and k= 1 x 10^10 N.M^2/C^2 will certainly close you in on the correct answer on all multiple-choice questions.

Knowing and memorizing

The practice exam is very much like the actual one. In particular, the front-page information that supplies you with some constants, a square-root table, and so forth is the same. What should you memorize?

Rote memorization entails the mental repetition of facts that does not involve the significance of, meaning of, or connection between, the facts. If you find yourself doing rote memorization you are likely to have a difficult time on the exam. Spend time instead a) understanding the relationship between various formulas, such as Coulomb's force law, force via electric fields, and the connection between electric potential and forces; and b) working though problems like those on the exam. I recommend your textbook and the textbook's web site for such problems. Attempt to find the smallest set of formulas and definitions from which you can derive everything else not by memorization but by association. Knowing the SI units associated with various quantities can help a lot. Thus, for example, Coulomb's law of force between charges, the electric field of a point source, and the potential of a point source are all terribly similar formulas. Knowing one should quickly get you to the other two. You may want to find yourself needing to memorize the definition of capacitance (C == Q/V), but once you do that, recognize that the formula for energy storage in a

capacitor is very closely related to the potential energy of a charge subject to an electric potential (U = CV^2/2 = QV/2 versus PE=qV).

You do not memorize the way to your friend's house and you certainly do not memorize the map to your friend's house even if you used one on the first one or two trips. You simply are familiar with the way. If you are driving today from the South whereas you usually come from the North, that's not a problem because you know the area and can even take a shortcut whether or not you have done so before. I do not advocate your memorizing anything to do well for the exam. I advocate your becoming familiar enough that you simply come to know the territory. A way that works for many people is to work problems --lots of problems. The text and text website, as well as the long-answer assignments, are good resources for problems similar to what you will find on both the practice and actual exams.

Practice reflects reality

I urge you to take the practice exam exactly as you will the actual exam. Do not at first use it to study for the exam, instead, study for the exam and then use the practice exam to assess your preparedness for the real one. If you do poorly on the practice exam, it is very likely you would do poorly on the actual one and you will need to do more studying to do well. If you do well on the practice exam, it is very likely you will do well on the actual one and probably you should go get some sleep. After taking the practice exam, yes, use the solution set to help you understand the material in preparation for the real exam.

You can now access the practice exam solutions under the Class Resources link. You will not be able to print the solutions, however.

Welcome to Physics 2020!

What about those microwaves soaking your brain while you talk with your friend on your cell phone? What are microwaves, anyway, and is it a good idea to have the phone at your ear for so long? What about that cool iPod, what makes it work? Physics 2020 is an introduction to the physical principles and the physical phenomena that govern an amazing variety of technology and much of the natural phenomena of which you are so familiar that you hardly notice.

Physics 2020, the second in the series of algebra-based physics courses, covers the subjects, of electricity and magnetism, really manifestations of simply one combined topic , electromagnetic phenomena. You will learn a great deal of electricity, of simple electrical circuits and circuits that use magnetic phenomena. You will better understand that radio waves, microwaves, and light are all really the same thing. You will come to understand how light can be manipluated with mirrors and lenses to make such useful things as cameras, microscopes, and eyeglasses to correct vision.