Static electric force is a non-contact force
What experiment will
you do to prove this?
Answers
Answer:
Scientific view
There are only two different sorts of known charge which scientists have labelled as ‘positive’ and ‘negative’. These names were chosen historically to indicate that they were somehow ‘opposites’ of each other, to help emphasise the two different observable forms. Scientists do not know exactly what charge is or how the two sorts of charge differ from one another; however each affects itself and its opposite form.
Positive and negative charged objects attract or pull each other together, while similar charged objects (2 positives or 2 negatives) repel or push each other apart. The charged objects do not need to be touching in order for the repulsive or attractive forces to be experienced between them; i.e. they can be observed to affect each other at short distances and without the need for any substance in between, e.g. air.
When an object made of a good electrical insulator like plastic or glass is rubbed vigorously with another flexible electrical insulator made from fur, cotton or wool it is possible for charge of one type to move from the surface of one insulator to the surface of the other. In Fig 1 below, before rubbing each item is electrically balanced. In Fig 2 below, after rubbing the plastic ruler has become negatively charged and the cotton positively charged. The rubbing does not create charges, but redistributes the charge between the two objects. As a consequence of their different overall charge, the two surfaces when separated will attract each other.
Charged objects can be created by using alternative methods to rubbing or sliding but all need the two surfaces to be in close contact and then separated. Other examples are peeling two plastic sheets apart or removing adhesive tape from a sheet of glass. Charged objects will also influence all other small ‘non-charged’ objects to become partially oppositely charged when they are brought near to them. This causes them to be attracted to each other. For example, a charged comb will attract small objects such as grains of sugar when brought close to them. If the grains of sugar come into contact with the comb then in a little while some of the grains will gain the same charge as the comb and will be rapidly repelled.
The amount of charge on the surface of any object will slowly reduce with time as the charge is eventually conducted away by water vapour in the surrounding air. For example a charged balloon will eventually fall from the ceiling as its charge diminishes.
Natural displays of charge movement like lightning mostly occur in storm clouds and less frequently above erupting volcanoes or in dust storms. In storm clouds, the charge is redistributed unevenly (parts will be positive and other parts negative).This imbalance can build up to the point where air becomes a conductor, and the imbalance is reduced by a rapid spark within the cloud or to the Earth. This is the lightning flash we see. The thunder we often hear is the result of this powerful spark rapidly heating the air.
Scientists are still trying to find out precisely why the imbalance of charge is created in storm clouds.
Explanation:
Answer:
Electrostatic forces are non-contact forces; they pull or push on objects without touching them. Rubbing some materials together can result in something called 'charge' being moved from one surface to the other.
Explanation: Flying Plastic Bag Experiment
Remember how the Harry Potter cast levitated their feathers using the ‘Wingardium Leviosa’ charm? Now you can too with the power of static electricity!
What you will need:
a plastic rod
a piece of cloth
a light plastic bag
Steps:
Rub the surface of the rod with the cloth for 40 seconds
Flatten the plastic bag and rub the cloth against its surface for 40 seconds
Release the plastic bag and watch it levitate as you wave the rod below
How it works: (Hint: It’s not magic!)
The rod and cloth gain become negatively charged after you rub them with a cloth. As like charges repel, the plastic bag appears to repel.