Section 9.1 Investigating Electrical Charges (p. 270) Questions: _________________________________________________________________________ ___________________________________________________________________________________________ Materials: _________________________________________________________________________ ___________________________________________________________________________________________ Hypothesis: ________________________________________________________________________ ___________________________________________________________________________________________ Procedure: STEPS 1. Inflate a balloon and equally space the letters A, B, and C around a balloon. Create a charge by rubbing a balloon against your hair. Place the balloon against several vertical surfaces. 2. Create a charge by rubbing a plastic ruler with fur or fleece. Place both close to the pieces of paper. 3. Create a charge by rubbing an overhead strip with fur. Hold the strip close to a stream of water. 4. Create a charge by rubbing an overhead strip with silk. Hold the strip close to a stream of water. 5. Create a charge by rubbing an overhead strip with fur. Mount the strip across a dish using the modeling clay. 6. Create a charge by rubbing a vinyl strip with fur. Bring the charged end of the vinyl strip close to the charged end of the strip mounted on the dish. 7. Place the uncharged part of the strip close to the charged end of the strip. 8. Create a charge by rubbing an overhead strip with silk. Repeat steps 5, 6, and 7. 9. Create a charge by rubbing an overhead strip with fur. Mount the strip on the dish using the modeling clay. Take a vinyl strip and create a charge by rubbing it with silk. Put both charged ends together. OBSERVATIONS Analysis & Communication Analyze your observations by answering the following questions. 1. Compare the behaviour of the balloon when parts A, B, and C were placed against the wall. What does this imply about the movement of the electric charges on the surface of the balloon? 2. What happens to uncharged objects when placed near charged objects? 3. What happens to the force exerted between charged and uncharged objects as the distance between them decreases? Support your answer with evidence from this investigation. 4. What evidence suggests that there are two kinds of electric charge? 5. From your observations, what can you infer about the behaviour of objects brought close to one another if they have like charges, and if they have unlike charges? 6. List the properties of electric charges you have identified in this investigation.