Negative Induction
Charging without contact using a negatively charged object
|
Induction
Show Me
The Physics
INduction - Charging w/o contact
Conduction and Induction
No charge is transferred Electrons redistributed
Conduction - Case II - Induction w/ Negative Rod
Frame 1 - Neutral Electroscope
#p = #e-
Frame 2 - Rod comes near
Compare #p with #e- #p = #e-
Electroscope is neutral
Knob (top) Positive Leaves - negative
Frame 3
Electroscope is neutral
Which diagram best represents the charge distribution on three neutral spheres when a positively charged rod is brought near sphere x, but does not touch it?
Jan. 2003 Regents
Choice 4 Electrons are attracted to rod
Why does a charged balloon stick to a wall?
Pith ball and negative rod
Show Me
The
Physics
School blocks YouTube? Pith Ball And A Charged Rod.mp4
What charge(s)
Negative or Neutral
|
||||
Check Your Understanding
5 quick questions — pick an answer to see if you’re right.
1. What is charging by induction?
2. A negative rod is brought near (not touching) the knob of a neutral electroscope. What happens?
3. While the negative rod is held near (not touching), what is the electroscope's overall charge?
4. A positive rod is brought near one end of a neutral metal sphere. How do the electrons move?
5. Why does a negatively charged balloon stick to a neutral wall?
Charging Without Touching
A negatively charged rod is brought near (but not touching) a neutral metal sphere on an insulating stand. While the rod is near, the far side of the sphere is briefly touched with a grounded wire. Then the ground wire is removed, and finally the rod is taken away.
What is the final charge on the sphere?
▶ Want a challenge? Open 6 more Regents-style questions (harder · mixed formats)
Challenge score: 0 / 6
C1. Before grounding, while the rod is near, which describes the sphere?
C2. A student makes the following claim.
Place a check mark in either the Support or Refute box. Justify your response.
C3. At the end of the process, the sphere has a charge of +3.2 × 10−9 C. Substitute numerical values into a mathematical representation that can be used to determine the number of electrons that flowed from the sphere to Earth. Then calculate the number of electrons.
C4. Place a check mark in three boxes to indicate the statements that are true at the instant just after the ground wire is removed, while the rod is still near the sphere.
C5. What happens if the student removes the rod before removing the ground wire?
C6. A lab needs to charge 20 metal spheres using one charged rod. Identify one advantage of charging the spheres by induction rather than by conduction, and one limitation of using induction.