science-chapter 19

what is all matter made out of?

atoms

what are three parts of and atom?

protons, electrons, and neutrons

what type of charge does a proton have?

a positive electric charge

what type of charge do neutrons have?

they do not have an electric charge

what type of charge do electrons have?

a negative electric charge

how much charge does an electrical charge neutral atom have?

equal numbers of positive and negative charge

do opposite charges attract?

yes.

what is Columbs law?

1. he more electric charge is present on two charged objects, the stronger the electric force between those charged objects will be.  They are __directly related__.
2. The farther apart two electric charges are, the *weaker* the electric force between them will be.  They are __inversely related__.

what is a good conductor of electricity?

a material that electrons can easily move across

what is not a good conductor of electricity?

a material that electrons can not easily move across

what is a good insulator of electricity?

a material that electrons can not easily move across

what happens when an object gives away electrons?

 it becomes __positively charged__.

what happens when an object receives electrons?

it becomes negatively charged.

what are 3 ways to electrically charge an object?

**conduction**, **friction**, and **induction.**

what is conduction?

the transfer of electric charge by simple touch.  Conduction happens when electric charges flow from one conductor to another (usually between metals).

what is friction?

charge by rubbing, one object scrapes electrons off of another object, and both become charged in the process

what is polarization?

when electrons concentrate, or scramble at one end of an object,

what is induction?

the transfer of electric charge by scrambling electrons in conducting materials.  a charged object *scrambles* the electrons in two conducting materials it is brought near by repelling the electrons in the conductors so that more electrons are on the far object (see page 351 for diagram).  when the conductors are separated, the charges are trapped and can’t return to where they were before

what is electric discharge?

when unbalanced charges become balanced

what is lightning?

lightning is a sudden electrostatic discharge that occurs during a thunderstorm. it is caused by the buildup and discharge of electrical energy between positively and negatively charged regions within a cloud or between a cloud and the ground.

what is an electric current?

the movement of electrically charged particles (electrons)

what is current?

the measure of how much charge is flowing through a circuit at any given moment measured in Amperes

what is resistance?

a measure of how difficult it is for electrons to flow through a material, measured in Ohms

what is voltage?

the amount of energy the source uses to move electrons through an electric circuit. 

does a good conductor have a ___________ resistance?

__low__ resistance.

does a bad conductor have a ________ resistance?

__high__ resistance

what does **Ohms Law** tell us?

\-the relationship among current, voltage and resistance in a circuit.

\-the greater the voltage in the circuit, the greater the current will be.  Voltage and Current are directly proportional. 

\-the greater the resistance in the circuit, the **less** the current will be.  Resistance and Current are inversely proportional.

what are the three basic parts of an electric circuit?

1. source of electric energy 
2. electrical devices that transform electrical energy
3. conductors such as wires that connect everything

what is a **series circuit?**

there is only **one** path for the current to flow.

what is a **parallel circuit?**

there are **many** paths for the current to flow

what is a **closed circuit**?

when a **complete path** exists between a battery’s negative and positive terminals,

what is a **short circuit**?

any complete circuit with no resistance (i.e. it’s connected to a battery, but not to any light sources or appliances)

what is electric shock?

when electric current flows through your body.