Try this at home!

Charged comb attracting a coke can

St. Mary's H.S. Physics YouTube Channel

School blocks YouTube? Use the file below.

PepsiComb.wmv

 

 

 

Grounded, neutral objects
gain or lose electrons by induction.

 

 

Case III - Negative rod/neutral object

[ Flash ]

 

Electrons are repelled down into the ground. Object becomes positive

 

 

 

 

Case IV - Positive rod / neutral object

 

[ Flash ]

 

 

Neutral object becomes negative as electrons are drawn up from the ground

 

 

 

 

Case V – Induction w/ grounded electroscope

St. Mary's Physics YouTube Channel

Where_did_the_charge_go_.mp4

 

1. A negative rod is brought near,
top touched, finger removed, rod removed.

2. A negative rod is brought near,
top touched, rod removed, finger removed.

 

 

 

 

 

Electroscope grounded

 

 

 

 

 

 

When Ground Removed,
Electroscope Maintains Charge 

 

Electroscope Charge?

 

 

Positive

 

 

Electrons left Electroscope

 

 

 

What would the charge on the the electroscope be if a positive rod were used?

 

 

 

Negative

 

 

 

 

Induction
(with grounding)
Rod Makes Electroscope
- +
+ -

 

 

 

Conduction
Rod Makes Electroscope
- -
+ +

 

 

 

 

 

 

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