1. A positive point charge Q1 = +Q is located at position (0,D) and a negative point charge Q2 = -2Q is located at position (L,D). What is the electric field at the point (x=L, y=0)? Express your answer in unit vector notation using the symbols given above and the constants k or 0. y L
Q1=+Q
Q2=-2Q D D x

2. What is the electric field at the point (x=L, y=0)?
Q1=+Q
Q2=-2Q D D E2   x E1

3. What is the electric field at the point (x=L, y=0)?
You could factor kQ out of the expression on the right hand side, but I don’t see that it simplifies anything much, so let’s put a box around our answer and call it done. L
Q1=+Q
Q2=-2Q D D E2   x E1

4. A negative point charge -q is placed at (x=L, y=0)
A negative point charge -q is placed at (x=L, y=0). What is the electric force on the point charge? Express your answer in unit vector notation using the symbols above and the constants k or 0. y L
Let’s be smart here…
Q1=+Q
Q2=-2Q D D -q x

5. Again, you could factor kQ out of the expression on the right hand side, or multiply both terms by –q. How about instead let’s put a box around our answer and call it done. y L
Q1=+Q
Q2=-2Q D D -q x