Re: How can i build an electroscope from common materials?

Hi Louise.

Once your electroscope is built I know you will be truely 
amazed at these unseen forces.  Imagine someone discovering such a device, 
yet having no knowledge of electricity.  How would she explain it?

Humans have a limited number of senses.  There are many parts of nature 
that we cannot detect.  Part of the great quest of science is to convert 
these undetectable forces into events that we can directly process and 
thus gain a valuable tool for better understanding our environment.

An electroscope responds to static electricity creating a motion that can 
be observed visually.  An electroscope usually consists of two thin metal 
leaves suspended from a metal hook. When the hook is brought near a source 
of static electricity, some of the electrons in the hook are pushed to the 
leaves (if the source is negative) or pulled up to the hook from the 
leaves (if the source is positive).  Either way, the leaves are now 
similarly charged and like charges repel each other.  The separation of 
the leaves is a funcition of the magnitude of this repulsion.  The 
magnitude of the repulsion is a function of the magnitude of the static 
charge at the top of the hook, which is proportional to the static charge 
on the test object if the distance between the test object and the hook is 
strictly maintained.

Cut two strips of foil lcm by 4cm.  Open out the paperclip so that it 
looks like a fish hook without the barb.  Push the hook through the middle 
of the index card and bend the top down on top of the card.  Use tape to 
secure the hook at right angles to the card. Lay the two foil strips on 
top of one another and hang them on the hook by pushing the hook through 
them. Lay the card over the jar so that the strips hang inside.

Bring various charged objects near the hook and observe what happens.
Notice what happens to the strips when the sources are removed.
Does anything different happen if the source actually touches the hook?
If the strips do not fall back together, gently touch the hook with your 
finger.

Electroscope design modified from  http://www.mos.or
g/sln/toe/simpleelectroscope.html


Please contact MadSci if you have any further questions.

Christopher Neale