Electric Charge (6.1 PS)
Presentation
•
Science
•
11th - 12th Grade
•
Practice Problem
•
Medium
Standards-aligned
Rachel Rapp
Used 29+ times
FREE Resource
16 Slides • 10 Questions
1
Electric Charge (6.1 PS)
2
Matter
As a quick refresher, matter is made of atoms. These atoms are made of protons (positive charge), electrons (negative charge), and neutrons (neutral charge).
The amount of positive charge in a proton is equal to the amount of negative charge on an electron. An atom has equal numbers of protons and electrons, so the charges cancel out and the atom has no net electric charge. Objects with no net charge are said to be electrically neutral.
3
Transferring Charge
Electrons are bound more tightly to some atoms and molecules. This means that when two surfaces come into contact, electrons from the less tightly bound substance can transfer to the more tightly bound substance. As a result, the substance gains extra electrons and becomes negatively charged. The substance that transferred electrons loses them and becomes positively charged.
4
Static Electricity
Static electricity is the accumulation of excess electric charge on an object.
5
Conservation of Charge
The Law of Conservation of Charge states that charge can be transferred from object to object, but it cannot be created nor destroyed.
6
Charges Exert Forces
Opposite forces attract each other, and same forces repel each other. The force between the charge depends on the amount of charge and the distance between charges. The force increases as the amount of charge increases and as the charges get closer together.
7
Electric Fields
Electric charges don't HAVE to be touching each other to exert a force. An electric field surrounds every electric charge and exerts the force that causes other charges to be attracted or repelled. Any charge placed in an electric field will be pushed or pulled by the field. Fields are usually represented by arrows that indicate how the field would make a positive charge move. So electric field arrows point away from positive charges and toward negative charges.
8
Conductors and Insulators
If you reach for a metal doornob after walking across a carpet, you might see a spark. This is caused by electrons moving from your hand to the doorknob. Recall that electrons were transferred form teh carpet to your shoes. How did these electrons move fro your shoes to your hand?
9
Conductors
A conductor is a material through which electrons move easily. Electrons on your shoes repel each other, and some are pushed into your skin. Because your skin is an effective conductor, the electrons spread over your skin, including your hand. The best electrical conductors are metals. Electrons in metals move easily, and so can transfer through the material with ease.
10
Insulators
Glass is an insulator. An insulator is a material in which electrons are NOT able to move easily. Electrons are held tightly to the atoms that make up an insulator. Most plastics are insulators, which is why you often see plastic coating around the wires of an electric cord.
11
Charging by Contact
Every example that we have given of charge transfer is an example of charging by contact. Charging by contact is the process of transferring charge by touching or rubbing. Rubbing two materials together can transfer electrons. Then one material is left with a positive charge (less electrons) and the other is left with a negative charge (more electrons).
12
Charging by Induction
Because electric forces act at a distance, charged objects brought near a neutral object will cause electrons to rearrange their position on the neutral object. The rearrangement of electrons on the surface of a neutral object by a nearby charged object is called charging by induction (think of holding a balloon near your hair, but not touching it).
13
Lightning
A thundercloud is a mightly static electricity generator. As air masses swirl and move in the cloud, areas of positive and negative charge build up. Eventually, enouugh charge builds up to cause a static discharge between the cloud and the ground. As the charges move through air, they collide with atoms and molecules in the aire to emit light .This creats a bolt of lightning.
14
Thunder
Lightning not only produces a brilliant flash of light, but it also generates powerful sound waves. The electrical energy in a lightning bolt rips electrons off atoms in the atmosphere and produces great amounts of heat. The surrounding air temperature can rise to about 30,000˚C, several times hotter than the surface of the Sun. The heat causes the air in the bolt's path to expand rapidly, generating sound waves that create thunder.
15
Grounding
Lightning strikes can cause power outages, injury, fires, and loss of life. The sensitive electronics in a computer an be harmed by large static discharges. A discharge can occur any time that charge builds up in one area. Providing a path for charge to reach Earth prevents any charge from building up. Any object connected to Earth by a good conductor will transfer excess electric charge through Earth. This is called grounding.
16
Electroscopes
An electroscope is a device that can detect electric charge. One kind of electroscope is shown to the right. It is made of two thin, metal leaves attached to a metal rod wiht a metal nob at th etop. The leaves are allowed to hang freely from the metal rod. When the device is not charged, the leaves hang down. When it is charged, electric forces push the leaves apart so they separate.
17
Multiple Choice
18
Fill in the Blank
19
Fill in the Blank
20
Multiple Choice
21
Multiple Choice
22
Fill in the Blank
23
Fill in the Blank
24
Multiple Choice
25
Multiple Choice
26
Multiple Choice
Electric Charge (6.1 PS)
Show answer
Auto Play
Slide 1 / 26
SLIDE
