Electric Force and Electric Field

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$a) What force does Trask exert on Butch? F - ^\ ~\â¢ *$

This is the formula for the field created by any point charge. It's also valid for the fieldcreated by a spherical charge for points outside of the charge. As mentioned earlier, thedirection of the field is radially outward for a positive charge. If Q is negative, the field willbe radially inward. The concept of electric field lines will help you visualize the field.These are continuous lines that begin on positive charges, end on negative charges, andsatisfy two criteria:1. The electric field at a given point is tangent to the field line that passes through that point.2. The density of field lines at a point is proportional to the strength of the electric fieldat that point.You'll find some examples in figure 4.Field lines start on + charges and end on -charges.The electric field is tangent to field lines.Figure 4Field Due to Point Charge DistributionsIf several point charges are present, you can calculate the total field using the principle ofsuperposition. This principle states that the total field at a point can be determined byfinding the contribution that each individual charge would make if it were the only chargepresent, then vector-adding all the contributions. For the principle of superposition to applyto a theory, certain conditions must be met by the laws that underlie the theory. Withoutgoing into the mathematical detail of the conditions, let s simply say that this principle canbe applied to both electricity and magnetism.Chapter 10
Physics B Review-4//C2//CFigure 5A -4 fiC charge is located at the point (0, 3), and a +2 ^C is located at the point(2, 0). Find the total electric field, magnitude, and direction at the origin (figure 5).You can find the field created by each charge separately, and then combine themusing vector addition.L4 = 9X 109 (4 X31°"6) = 4 X 103 £ (+y direction)£+2 = 9 X 109 (2 X21°"6) = 4.5 X 103 -g- (-x direction)You can use basic trigonometry to find the magnitude and direction.E = E\2 = 6.02 X 1Q3= %7 = l^Motion of a Charge in an Eleqric FieldIf you happen to know the field at a given point, you can use the definition of an electricfield to find the force on a charge that's placed at the point, assuming the introduction of thecharge doesn't change the local charge distribution and the field.F" = qtThis equation gives you the force on a charge q placed at a point where the field is E.Electric Force and Electric Field
Page 1 and 2: CHAPTEElectric Force and Electric F
Page 3: Physics B ReviewBecause both charge
Page 7 and 8: PRACTICE EXERCISESSection I Multipl
Page 9 and 10: Physics B ReviewFigure 92. A noncon
Page 11 and 12: Physics B Review3 x IP"6 _ , 6 X IP

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