3.2 - Static Electricity and Conduction Flashcards
What does the term Electrostatics refer to?
Electrostatics deals with electrical charges at rest
What is the force of attraction between the electron and the proton known as?
The force of attraction of an electrostatic force
Coulomb’s Law states:
Like charges repel
Unlike charges attract
What does the force between unlike charges depend on
This force depends on the distance between the charges and amount of charge
What equation describes the force of attraction of two unlike charges and how is this expressed
The force of acting between two charged objects is proportional to the products of their charges and inversely proportional to the distance between them.
The force of repulsion or attraction varies as the inverse of the square of the distance between the charges
What is the ‘‘Triboelectric Series’’?
Materials differ in their ability to attract or give up electrons. This is dependent on where the materials appear in the ‘‘Triboelectric Series’’
What is the difference between induction and conduction?
In contrast to induction, where the charged object is brought near but never contacted to the object being charged, conduction charging involves making the physical connection of the charged object to the neutral object. Because charging by conduction involves contact, it is often called charging by contact.
What is an earth wire?
An object that might become charged is connected to the earth by an earth wire, so any charge immediately flows down the earth wire.
What happens when a glass rod is rubbed with a silk cloth (charges)
We know that when a glass rod is rubbed with a silk cloth, the glass gives up electrons to the silk. As a result, the glass becomes positively charged while the silk becomes negatively charged.
How is the distribution of charge on objects?
The distribution of the charge on an irregularly shaped object differs from that on a regularly shaped object. In all cases where a charge forms on an object, the electric field strength will be the greatest at the object’s extremities or sharp edges.
All effects of electricity are due to the displacement of _____. When this displacement causes a charge to develop on an object, an ______ _____ about the charge will result.
When the displacement causes a current flow, then ……
electrons
electric field
a magnetic field around the current will result.
What results when current passes through a resistance?
Electrons require a medium through which they can flow and a _____ to push or pull them. This force exists because of the action of electric or magnetic fields. The dynamics of electron displacement, or conduction, is different in ____, ____, _____ and ____
Heat
Force
Solids, Liquids, Gases and Vacuum
In general the presence of ions in a liquid determines its conductivity. Elaborate
In the absence of ions the liquid becomes an insulator.
Distilled or de-ionised water is devoid of ions and is a very good insulator
Salt water however, is a good conductor, containing a large amount of ions provided by the distilled salts.
A solution containing ions conducts electrons when a potential difference is applied across it.
When does Electrolysis occur?
Electrolysis occurs when the applied voltage is high enough to break the water molecule ionic bond.
Current flows when the ions touch the electrodes.
Can gases conduct electricity and if so describe how.
Any gas in its neutral state, i.e the molecules are not ionised, cannot conduct electricity and is in fact an insulator, yet under certain conditions, a breakdown of the insulating property occurs, and current can pass through the gas.
This is brought about as follows:
Combustion (Chemical Reaction)
Heat (Thermal Agititation)
Exposure to Ionising Radiation ( e.g Cosmic rays, sunlight) High Voltage (Electrical Stress)
Friction
What does current flowing in a vacuum look like (diagram)
