-L-L L P ConcepTest #5: Assume that a strip of tape, length 2 L, has a uniform charge distribution and is oriented as shown. What is the direction of the electric field at the point P ? What is the electric field at the point P ?

-L-L L P dQ ( x,y ) 10.Take a nap, because you’re probably exhausted!

-L-L L P dQ ( x P, 0) ( x,y ) ConcepTest #6: Which of the following best represents ? ( x P, y P ) ( 0,y )

-L-L L P dQ xPxP ( 0,y )

-L-L L P dQ xPxP ( 0,y )

-L-L L P dQ xPxP dL = dy For uniform charge distribution, then  constant; here = Q /2 L Limits? Look at integration variable and charge distribution...

-L-L L P dQ xPxP Think about This: Earlier we said that the y- component of the electric field for this configuration will be zero due to symmetry. Prove this explicitly by evaluating the integral for the y -component of the electric field.

Some possibly useful integrals (not an exhaustive list!)

-L-L L P dQ xPxP ConcepTest #7: Consider the case where L gets very large compared to x P. Which of the following best represents ?

Electric field of special charge distributions “infinite” uniform line charge: points perpendicular to line, with y = perpendicular distance from line uniform ring of charge (on axis): points along axis, with a = radius of ring; r = distance along axis uniform disk of charge (on axis) points along axis, with R = radius of disk; x = distance along axis “infinite” uniform plane of charge: points perpendicular to plane