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2. 1 of 3 • Lightweight conductive sphere A hangs by a string and is free to swing like a pendulum. Identical conductive sphere B is fixed by an insulating rod. Both are initially electrically neutral. An amount Q of positive charge is then transferred from B to A (leaving B with an amount Q of negative charge). When A is brought close to B, • A swings toward B (as shown). • A swings away from B (not shown). • A hangs straight down (not shown, no interaction). −Q +Q − + B − − A + + − − + + − − + + − + 2

3. 2 of 3 • Lightweight conductive sphere A hangs by a string and is free to swing like a pendulum. Identical conductive sphere B is fixed by an insulating rod. Both are initially electrically neutral. An amount Q of positive charge is placed upon A. When A is brought close to B, • A swings toward B (as shown). • A swings away from B (not shown). • A hangs straight down (not shown, no interaction). +Q + B A + + + + + + + 3

4. 3 of 3 • Lightweight conductive sphere A hangs by a string and is free to swing like a pendulum. Identical conductive sphere B is fixed by an insulating rod. Both are initially electrically neutral. An amount Q of positive charge is placed upon A. B is grounded. When A is brought close to B, • A swings toward B (as shown). • A swings away from B (not shown). • A hangs straight down (not shown, no interaction). +Q + B A + + + + + + + 4

5. Announcements: • Take any remote, enter 6-digit student ID. • Log onto MasteringPhysics ASAP and make sure you can see assignments. First assignment due Friday 7:30 am.

6. TRIBOELECTRIC SERIES

7. 1 of 3 • Lightweight conductive sphere A hangs by a string and is free to swing like a pendulum. Identical conductive sphere B is fixed by an insulating rod. Both are initially electrically neutral. An amount Q of positive charge is then transferred from B to A (leaving B with an amount Q of negative charge). When A is brought close to B, • A swings toward B (as shown). • A swings away from B (not shown). • A hangs straight down (not shown, no interaction). −Q +Q − + B − − A + + − − + + − − + + − + 7

8. 2 of 3 • Lightweight conductive sphere A hangs by a string and is free to swing like a pendulum. Identical conductive sphere B is fixed by an insulating rod. Both are initially electrically neutral. An amount Q of positive charge is placed upon A. When A is brought close to B, • A swings toward B (as shown). • A swings away from B (not shown). • A hangs straight down (not shown, no interaction). +Q + B A + + + + + + + 8

9. 3 of 3 • Lightweight conductive sphere A hangs by a string and is free to swing like a pendulum. Identical conductive sphere B is fixed by an insulating rod. Both are initially electrically neutral. An amount Q of positive charge is placed upon A. B is grounded. When A is brought close to B, • A swings toward B (as shown). • A swings away from B (not shown). • A hangs straight down (not shown, no interaction). +Q + B A + + + + + + + 9