| |
 The tool to test
whether an object
is charged
or not is an
electroscope;
an example is
shown in
the following figure.
In an electroscope,
a pair of light metal
foils are hung down
from an electrode
in a container
of an insulator
like a glass bottle
as shown in the figure.
If we touch
a charged object
to the electrode
of the electroscope,
then the metal foils
charge and
they open
the angle
between the foils
due to the repulsive force.
The angle may roughly
indicate the amount
of the charge.
Since an electronic
device with high accuracy
is used today,
this type of electroscope
is no longer used
except for educational
purpose.
|
