10.1 Exploring Static Charges - I
What is electricity?
a form of energy that results from the interaction of charged particles, such as electrons and protons
what is static electricity?
an electric charge that tends to stay on the surface of an object, rather than flowing away quickly
what is an electroscope?
a device for detecting the presence of an electric charge
what is an ion?
a charged atom or group of atoms
What is charging by friction?
a process in which objects made from different materials rub against each other, producing a net static charge of each of the objects
What is the purpose of grounding?
the simplest way to remove the net static charge on an object is to put it in contact with the ground.
What is the difference between charging by contact and by induction?
contact: generating a charge on a neutral object by touching it with a charged object
induction: generating a charge on a neutral object by bringing it close to (not touching) a charged object
what is an electrostatic precipitator?
type of cleaner that removes unwanted particles and liquid droplets from a flow of gas
What is the difference between the following: i) insulator, ii) conductor, and iii) semiconductor. Give an example for each.
insulator: material in which electrons cannot move easily from one atom to another (e.g. wood)
conductor: material in which electrons can move easily between atoms (e.g. copper)
semiconductor: material in which electrons can move fairly well between atoms (e.g. silicon)
List 5 examples of conductors
Iron, copper wires, human body, metal pan, salty water
you are using the metal leaf electroscope and a negatively charged rod is brought close it - what will happen to the leaves?
spread apart due to presence of an electric charge
(excess of electrons from rod flow through the setup of the electroscope, both metal leaves end up being charged by the same charge and repel)
what is the special conducting property of selenium?
different light conditions affect the ability of selenium to conduct
How do anti-static sheets (e.g. dryer sheets) work?
clothes are made from many different materials and when they rub together in the clothes dryer, generating static charges on the surface of these materials.
anti-static sheet is small piece of cloth that contains a waxy compound, which coats the clothes. This causes clothes to behave as if they were made from the same material
what happens to the number of electrons and protons when the static charge is net positive or net negative?
Net positive: less electrons than protons
Net negative: more electrons than protons
what is an electric field and how is the strength of electric field related to net charge?
electric field is a property of the space around a charged object, where the effect of its charge can be felt by other objects.
stronger electric field if net charge is higher
what is a lightning rod and what are its two functions?
metal sphere or point, attached to the highest part of a building and connected to the ground
functions:
reduce likelihood of a lightning strike and if strike occurs, conduct the charge safely to the ground
If a silky cloth was rubbed against human hair, which material would have a positive charge and which one would have a negative charge? What causes the formation of these charges?
(hint: table 10.1)
Silk would be neg. charged because electrons from the hair would get transferred onto it. Hair will be pos. charged. Silk gets the excess of electrons because it has a stronger hold on electrons
You have two different materials, how can you tell which one would have a stronger hold on electrons?
Look at electrostatic series table and see which one has stronger hold on electrons - that material will be neg. charged if it as to be rubbed against the 2nd material
What are the 3 laws of electric charges?
1. Like charges repel.
2. Opposite charges attract.
3. Charged and neutral objects attract each other.
what is a van de graaf generator and give two of its uses?
a device that accumulates very large charges
uses:
- used in atom smashers; it can accelerate particles to very high speeds.
- test electronic circuits used in space technology