Sign
The answer that you submitted suggests that you have misinterpreted the sign when attempting to solve the Charged spheres demo question. If you cannot find a section below that helps resolve your error, please visit the feedback discussion page or try the charged spheres demo question again.
Magnitude
The value that you submitted is the model magnitude but incorrect sign. This error could be due to missing the sign on the known charge or the direction of the electric field.
Please try again and read the question carefully.
Square
The value that you submitted is the square root of model magnitude with an incorrect sign. The sign error could be due to missing the sign on the known charge or the direction of the electric field. Submission of the square root of the model answer can indicate a conceptual difficulty with Coulomb's law and/or the electric field.
Please review Coulomb's law and electric field for charged spheres and try again.