Electricity Notes (10.1, 10.2, 10.3) PDF

Electricity Unit Greeks found electricity. All matter is made of atoms. Atoms contain smaller particles: protons, neutrons and electrons. Some of these particles have an electric charge. E.g protons= p+, neutrons= n0, electrons= e- If an object has more electrons than protons it is ne...

Electricity Unit Greeks found electricity. All matter is made of atoms. Atoms contain smaller particles: protons, neutrons and electrons. Some of these particles have an electric charge. E.g protons= p+, neutrons= n0, electrons= e- If an object has more electrons than protons it is negatively charged. If an object has more protons than electrons it will be positively charged. If an object has equal electrons and protons the object is neutral. The movement of electrons creates electricity. Law of attraction: Opposite charges attract. Law of repulsion: Same charges repel each other. A charged object and a neutral object will attract each other.  Electrons can be transferred from one object to another. Eg. a neutral or positively charged will become negatively charged object will become negatively charged if it gains electrons. Similarly, a neutral or negatively charged object will become positively charged if it loses electrons. Only electrons (negative charges) are able to move. Different substances have different abilities to hold on to electrons. The tendency of a substance to hold on to the electrons is called electron affinity. Tendency to lose electrons: Human skin, glass, wool, cat fur. Tendency to gain electrons: Polyester, wood, balloon, rubber. Another name for electron affinity is electrostatic series. Conductivity is the ability of materials to allow electrons to move freely. Material that holds to their electrons and doesn't move them easily is called the insulators. In an insulator the electrons are bound tightly to the nuclei, so they resist movement.  Materials that allow electrons to change positions are called conductors. In a conductor the electrons are not tightly bound to the nuclei and therefore move away from the nuclei. Electricity: A form of energy that results from the interactions of charged particles, such as electrons and protons. Static charge: An electric charge that tends to stay on the surface of an object, rather than flowing away quickly. Charging by friction: A process in which objects made from different materials rub against each other, producing a net static charge on each object. Electrostatic series: a list of materials that have been arranged according to their ability to hold on to electrons. For example in a glass and silk if we rub the silk it will be greater affinity for electrons because it likes more electrons. The electric charge that builds up on a surface of an object is called a static charge. The charges are ‘static’ because they remain in one location on the surface of the object until they are given a path to escape.  All solid materials are charged by the transfer of electrons. When two objects rub together, the force of friction can remove electrons from one object and transfer them to another object. Why would we want to slow down the movement of electrons? As one object loses electrons, the other object gains them. New electrons are not being made, they are just being transferred. Transferring electrons by rubbing action or friction, i.e socks on a carpet. The force removes electrons from one object and transfers them to other objects. - Objects that lose electrons become positive. - An object that gains electrons becomes negative. Electrons are passed from one object to another when they touch. The neutral object will always gain the same type of charge as the object that touched it. Created permanent charge. If the rod is positive the electrons will go towards it. If the rod is negative the electrons will repel and go apart from it.  Induction is when we don’t touch it but the electrons will go towards where they want to go. Induction is a temporary charge. - Occurs without direct contact. - Involves movement of electrons within a substance. - Electrons in a neutral object move closer to or away from a nearby charged object. Protons don’t move. Positive charges appear to ‘ move’ because electrons were gained in one place and lost in another place. Learning check questions. Page 426. - 5) In a spray painter the charge is opposite of the object that we are spraying on so they attract and are coated on the surface of the object. - 6)Good conductors of electricity when exposed to light. - 7)Since it can generate a lot of charge they use it in atom smasher to break them down. - 8)The positive charge. Content needs to know. 1- Improved transfer efficiency = cost decrease of manufacturing. Review question 10.2: 1: Charging by contact is when two objects touch and the electrons move from one to another. Friction is when we rub two objects and the electrons are transferred to the one that has greater affinity. Charge by induction is when one object is neutral and the other one is either negative or positive and when it gets close to the other object the opposing charges interact. 2: The electroscope has a positive charge that is why they repel each other. 3: It gets weaker as the distance is further. 4: Because insulators take the electrons and they don’t give them away easily so the flow of electricity would not be there if it used materials that are insulators. 5:a) The wall is charged by contact because we are sticking the balloon to the wall. b)When the balloon and the wall transfer the electrons the balloon becomes positive so it falls down. 6: If the pitch ball is moving towards that rod, yes it is positive. Because if it was negative they would repel each other. 8:a) Positive charge. b)If we put the rod close to both spheres their electrons will move towards that rod because opposite energies attract. c) If we do this the same thing will happen with the first example but it will happen with only one sphere. d)The charges would be the same but the placement of electrons and the positive particles would go back to the original placement. Insulator: a material that does not allow the electrons to move easily. Conductors: Materials that allow electrons to move easily between atoms. Semiconductor: Material that allows electrons to move fairly well between atoms, which means it does not give all its electrons away fast and easily and it also does not hold on to them. Ground: An object that can remove a very large number of electrons from a charged object so it makes the object neutral. Chapter 10 review questions 1)Electro static series. 2)Conductors. Insulators. 3)Electroscope. 4)Sparking. 5)Lightning rod. 6)Electrostatic participator. 7)They can interact through induction when the two objects get close to each other. 8)When it was rubbed, friction was made and the object that has a greater affinity to negative charges takes the negative charges from the other one. In this case the polyethylene is more affinity to electrons so it gains more electrons and it becomes more negative. 9)The ground takes a large amount of electrons from that object making it neutral. 10) Atoms sometimes need electrons or to get away from the electrons so they can have a last full shell so they become stable. Insulators are materials that gain the electrons and hold on to them tight and don’t let them move. Conductors are the one that need to give away electrons to become more stable so they easily let it go. The  difference is conductors give away electrons, but insulators take and keep them. 11) Because the movement of electrons determines the charge of the object. 12) Because the opposite charges of each object attract each other. 13) 14) Law of attraction. 15) They can generate a lot of electricity so they are able to break atoms down. 16) 17) Thighs that would be on the test: Charging by friction:When two objects are rubbed together and the object that has a greater affinity for electrons will gain the electrons from the other object and in result both objects become charged. Static charge: The amount of charge that is created on a surface of an object. Electrostatic series: It's a series that is defined by how much affinity objects have for electrons.  Causes of electric charges Conductors, Insulators, Affinity. Conductors allow electricity to move freely between objects. Insulators take the electrons and they don’t allow them to move easily. Affinity is how bad an object wants electrons. Antistatic sheets, water as a conductor/insulator. Grounding: Is a way that can remove electricity from an object so it makes it neutral. Shocks: Charging by contact/ Induction: Charge by contact is when two objects touch and the electrons are transferred from one object to another. Charge by induction happens when there is no contact and no electrons are transferred, it’s when two objects get close together and opposite charges of those two objects attract each other. Electroscopes/Pitballs: Electroscope is a device that helps to see if an object is charged or not. Pitballs are a part of electroscopes where the positive and negative charges are located. The laws of electrostatic charges: opposite charges attract, same charges repel each other. Giving an object -ve/+ve charges. Electric fields.  Induced charge separation Lightning Lightning rods Electrostatic precipitator Electrostatic spraying photocopies/printers Lab info Videos. Semiconductor: Materials that move electrons fairly between atoms meaning they don’t allow them to move quickly like conductors nor they hold on to them like insulators, they are somewhere in between. Example of semic conductors: silicon, germanium. Electric fields: A property of the space around a charged object , where the effect of an object charged can be felt by others. As the distance from that object increases the electric field’s effect decreases. Objects with stronger (more) net charges will have the stronger the electric fields. Induced charge separation: The movement of electrons in a substance, caused by the electric field of a nearby charged object , without direct contact between the substance and the object.  Lightning: happens because of a large charge imbalance between clouds or the clouds and the ground. If the imbalance is great enough it will find its way to the ground in a huge spark. Air in and around the clouds separates the negative and positive particles so the imbalance happens and the negative charges get attracted to positive stuff in the ground so the lightning would use water vapour in the air to strike the positive things like trees or conductors on the ground. Lightning rods: A metal sphere or point, attached to the highest part of a building and connected to the ground. The rapid transfer of excess charge is called an electric discharge. Electrons transfer from the more negative object to the less negative object. Between steele and cat fur the steele would be negative