Difficulty 3 - Force a charge around multiple physical barriers and into the net using fixed charges. 1. Click the Reset and Clear buttons and select Difficulty: 3. Your goal is to get the black positive charge around the physical barriers and into the net. 2. Add and move charges by clicking and dragging each charge. 3. Click the Reset button. 4. Release the black positive charge by clicking the Start button. Note the relationship between the charge's path and the strength and direction of the electric field along its path