Induced Charge on Electroscope
Purpose
Demonstrates charging by induction using a needle electroscope. A charged rod induces charge separation; grounding while the rod is nearby permanently transfers charge of the opposite polarity. Test the sign of the acquired charge by bringing rods of known polarity near the electroscope.
Figure 1:
Complete setup: needle electroscope at rest (neutral), Teflon and acrylic charging rods with fabric pads, and CENCO grounding stand with alligator clip.
Figure 2:
The needle deflects when the charged Teflon rod approaches, showing induced charge separation in the electroscope.
Figure 3:
Grounding the electroscope while the charged Teflon rod remains nearby allows like charges to flow to ground.
Figure 4:
After removing the ground first, then the rod, the electroscope retains a net positive charge (opposite to the negative Teflon rod).
Figure 5:
Testing polarity: the acrylic rod (positive when charged) brought near increases deflection, confirming the electroscope carries positive charge.