Iona Prep Physics Lab

Investigating Electrostatic Charges

Materials:

Aside from the electroscope, pictured above, you will have available the following equipment

Clear plastic strip

Plastic Rod (clear, solid)

Rubber Rod (black, solid)

Green Plastic Strip

Piece of silk

Piece of fur

Piece of Flannel

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For the purposes of this experiment, assume that when the Rubber Rod is rubbed on fur it acquires a net negative charge.

Procedure:

Charge the electroscope by Contact with the rubber rod which has been charged by rubbing on fur.

(A)   Test the charge developed by the Clear plastic strip rubbed with silk.  What effect does it have on the electroscope?  Does the charge on the glass rod appear to be positive or negative?

(B)   Test the charge developed by the clear plastic rod rubbed with silk.  What effect does it have on the electroscope?  Does it the charge on the plastic rod appear to be positive or negative?

(C)   Test the charge developed by the green plastic strip rubbed on flannel.  What effect does it have on the electroscope?  Does the green strip appear to be positive or negative?

Charge the electroscope by Induction with the rubber rod which has been charged by rubbing on fur.

(D)   Retest the charge developed by the clear plastic striprubbed with silk.  What effect does it have on the electroscope?  Does the charge on the glass rod appear to be positive or negative? Is this consistent with the results found in step A?

(E)    Retest the charge developed by the clear plastic rod rubbed with silk.  What effect does it have on the electroscope?  Does it the charge on the plastic rod appear to be positive or negative?  Is this consistent with the results found in step B?

(F)    Retest the charge developed by the green strip rubbed on flannel.  What effect does it have on the electroscope?  Does the green strip appear to be positive or negative?  Is this consistent with the results found in step C?

Conclusion:

For each item A,B,C

Because the electroscope was charged [positive, negative] and the leaves [diverged-collapsed-did not respond], I conclude that the ____ was charged [positive, negative, neutral].

For each item D,E,F

Because the electroscope was charged [positive, negative] and the leaves [diverged-collapsed-did not respond], I conclude that the ____ was charged [positive, negative, neutral]. This [confirms – contradicts] the previous results.