Electric Charges 03  Electric Fields 
OPENING QUESTIONS: What are the SI Units for an electrical field? What do those units tell us about the nature of an electric field? OBJECTIVE: I will be able to sketch the electrical field lines between two point charges (either positive or negative) after today's class WORDS/FORMULAE FOR TODAY Terms:
Constants:
Formulae:
WORK O' THE DAY: Let's get our homework on the board  be prepared to answer questions about the problem: 4, 10, 15 first 26, 33 next ═══════════════════════════ Let's take a gander at the opening question Our mostgraciousandhumble author kind of glosses over his discussion of field lines... for a somewhat more comprehensive discussion please take a look at THIS (from the physicsclassroom.com) ═══════════════════════════ ACK! A problem with the "Pitfall Prevention 23.2" on page 709. A VERY helpful way to help us understand the nature of electrical field lines is for us to 'place' a test charge between two objects with electrical charge. In that thought experiment, the test charge "follows" the field lines between those two objects. As you might expect the test charge (since it is positive) will move towards the negatively charged object along those field lines and away from a positively charged article once again following the path outlined by the electrical field lines. HOWEVER, what that Pitfall Prevention is trying to tell us is that in the REAL WORLD, objects rarely follow such proscribed paths... Consider again a comet moving through the solar system. We can very adequately predict the general motion of the comet by sketching gravitational field lines emanating from the sun. In such a situation, the comet follows a proscribed parabolic orbit described by those field lines.... However, in the 'real' world, that comet experiences perturbations in its orbit as it moves closer to the planets. The closer it gets to the larger planets, the more its orbit is disturbed. The Rules for drawing electrical field lines:
With that in mind: work with your groups to sketch the field lines between the following situations: 1) two point charges with +q and q charges a distance 'r' apart 2) two point charges with +q and +q a distance of 'r' apart 3) two point charges with +2q and q a distance of 'r' apart 4) two point charges with q and  q a distance of 'r' apart ═══════════════════════════ HOMEWORK: Sketch 1, 2, 3 & 4 above Conceptual Problems C23.1 and C23.4

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