When does electrostatic force appear? Does moving a bent finger closely to a van degraff generator considered to exhibit electrostatic force?
Electrostatic force appears whenever there are stationary electric charges, also known as static charges. It is the force of attraction or repulsion between these charges.
In the case of a Van de Graaff generator, electrostatic force is indeed present. The Van de Graaff generator accumulates static charge on its metal dome, and when a charged object - such as a bent finger - is brought close to the generator, there will be an interaction between the charges.
To understand why this interaction occurs, we can consider the principles of electrostatics. When the bent finger approaches the Van de Graaff generator, it interferes with the electric field surrounding the generator. This disturbance leads to a redistribution of charges on both objects.
The Van de Graaff generator may induce a charge in the bent finger, causing it to become charged as well. The interaction between the charges on the finger and the charges on the generator will result in the attraction or repulsion forces characteristic of electrostatics.
To further investigate and determine the nature of the force experienced when moving a bent finger close to a Van de Graaff generator, you could perform experiments measuring the force between the objects using appropriate tools such as an electrostatic force meter. This would allow for a more precise evaluation of the forces involved.