A pith ball electroscope works on the same principle as the foil leaf electroscope, but looks a little bit different. To make a pith ball electroscope you will need:


A small piece of aluminum foil
A foam cup
An aluminum pie plate
A plastic straw
Hot glue or tape
Thread
A balloon
A foam plate
A ruler
Scissors

, Make two holes near the bottom of the cup on opposite sides and slide the straw into place. Position the straw so that three to four inches sticks out on one side of the cup.


Secure the straw to the cup with tape or a little bit of glue.
Avoid making the holes too large or ripping the base of the cup.
It’s okay if the base of the cup has a hole in it as long as the straw is stable in its place.
 Turn the cup upside down so that the bottom of the cup is facing up. Tape or glue the top of the cup to the pie plate. Position the cup towards the edge of the pie plate so the straw sticks out over the edge.Make sure to secure the cup firmly to the bottom of the plate.
Use caution when using hot glue as it is very hot and can cause burns.
 Measure and cut out a one-inch square of aluminum foil. Crumple it tightly into a spherical shape. Try to make it as evenly crumpled as possible so that it looks like a foil marble.The square does not need to be exactly 1-inch, it just needs to be a small marble-shaped aluminum ball.
 Cut a piece of thread long enough to hang the foil ball from the straw without it touching the table (about 2-3 inches should be enough). Tie the thread around the foil ball and knot it in place. Tape the other end of the thread to the end of the straw. The foil ball should hang straight down from the end of the straw.


Make sure the foil ball hangs close to the edge of the pie pan, but does not touch it.
 Rub the foam plate against your hair or a rubber balloon to charge it with static electricity. Place the electroscope on top of the plate and observe what happens. The foil ball should move away from the pie plate. The foam plate transfers electrons to the pie plate and gives it a negative charge, repelling the foil ball away from it.When picking up or moving the electroscope, carry it by the foam cup. If you touch the pie plate, the charges will change and it will not work properly.
Gather your materials.
Push a plastic straw through the bottom sides of the foam cup.
Attach the top of the cup to the pie plate.
Crumple a 1-inch square piece of aluminum foil into a ball.
Hang the foil ball from the straw with a piece of thread.
Test the electroscope with a charged foam plate.
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