1) A small object with a net negative charge is placed at the location shown below near a large negative source charge Determine (a) the direction of the force exerted on the small object by the source charge and (b) the direction of the -field at the location of the small object. Scientific Abilities Can relate electrically charged objects to the E-field in the space surrounding them Missing No relation is made between electrically charged objects and the E-field surrounding them. Inadequate The E-field and electrically charged objects described are not consistent with one another or important elements are missing. Needs Improvement The E-field and electrically charged objects described are consistent with one another but minor mistakes or omissions were made. All aspects of the E-Field or objects may not have been considered or the superposition of multiple influences was not considered. Adequate The E-field and electrically charged objects described are consistent with one another and are described in full detail with no errors or omissions. Explain how the (a) force exerted on the small object by the source charge and (b) the value of the E-field at the location of the small object would change if the magnitude of the small object's charge were doubled. Scientific Abilities Can relate electrically charged objects to the E-field in the space surrounding them Missing No relation is made between electrically charged objects and the E-field surrounding them. Inadequate The E-field and electrically charged objects described are not consistent with one another or important elements are missing. Needs Improvement The E-field and electrically charged objects described are consistent with one another but minor mistakes or omissions were made. All aspects of the E-Field or objects may not have been considered or the superposition of multiple influences was not considered. Adequate The E-field and electrically charged objects described are consistent with one another and are described in full detail with no errors or omissions. Use the charge of the small object (-9) and the force exerted on it by the large source charge (-Q) to derive an expression for the magnitude of the E-field a distance r from the source charge. Scientific Abilities Is able to represent a situation with mathematics Missing No representation is constructed. Inadequate Mathematical representation lacks the algebraic part (the student plugged the Needs Improvement Mathematical representation is represented symbolically (not just using numbers) and numbers right away) has the applies appropriate physics wrong concepts being applied, or signs are incorrect. concepts to the situation. No evaluation of the math in the problem is present. Adequate Mathematical representation is represented symbolically (not just using numbers) and applies appropriate physics concepts to the situation. The mathematical representation is evaluated for its appropriateness and consistency.