Find the Electric field strength at a point between two charges

[rocapp]

Homework Statement

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Homework Equations

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The Attempt at a Solution

I have tried parts C and D several times, and the homework program is telling me that it's still not correct. For C, I keep getting:

7.7x10^8 N/C

for D I keep getting:

7.1x10^-12 N/C

In order to find these, I know you just plug in the known values into the equation from part A. But each time I plug these in, I get an incorrect answer. Please help. Thanks in advance!

 

[SammyS]

Homework Statement

See images

Homework Equations

See images

The Attempt at a Solution

I have tried parts C and D several times, and the homework program is telling me that it's still not correct. For C, I keep getting:

7.7x10^8 N/C

for D I keep getting:

7.1x10^-12 N/C

In order to find these, I know you just plug in the known values into the equation from part A. But each time I plug these in, I get an incorrect answer. Please help. Thanks in advance!

For parts C & D please show your work, i.e. show exactly what numbers you are putting into your formula.

You are using millimeters and nanoCoulombs, aren't you ?

 

[rocapp]

Oh! Units were the problem. Does this change the value of the permittivity constant from 8.85x10^-12 F/m to 8.85x10^-9 F/mm?

 

[rocapp]

That is correct. I fixed the problems. Thanks!