NAME:_____________________________________DATE:___________PERIOD:___
Static Electricity - Chapter 20
Chapter 20, Section 1 – Electric Charge
Main Idea - Like charges repel, and unlike charges attract
Evidence of Charge
Electrostatics is the study of ___________________ that can be collected and held in
one place.
Scientists have determined that there are __________ types of electric charge
____________________________ named them positive and negative charges
Two objects with like charges always _______________________________.
Two objects with unlike charges always ________________________________.
If you rub your hair with a balloon, it will stand on end because of the ________________
________________ between your hair and the oppositely charged balloon.
A Microscopic View of Charge
All materials contain light, negatively charged particles called _____________. In
addition, each atom has a massive, positively charged nucleus, containing ____________.
For a neutral object, the amount of positive charge exactly _____________ the amount of
negative charge.
With the addition of energy, the ______________________ can be removed from atoms.
An atom missing electrons has an overall __________ charge, and consequently, any
matter made of these electron-deficient atoms is positively charged.
The freed electrons can remain unattached or become attached to other atoms, resulting in
___________________ charged particles.
Electric charge carriers are electrons rather than protons because the electrons:
Have a __________________ mass
Are located ___________________________________
Are loosely bound to the ___________________
From a microscopic viewpoint, acquiring charge is a process of _____________________
_______________________.
If two neutral objects are rubbed together, each can become ___________________.
For instance, when rubber shoes are rubbed on a wool rug, electrons are removed from the
atoms in the wool, and transferred to the shoes.
The extra electrons on the rubber result in a net ______________ charge. The electrons
missing from the wool result in a net ______________charge.
Charge is conserved. This is, individual charges never are created or destroyed, they just
______________________________.
Have you ever experienced an electric charge?
Ever been shocked by a door knob or car door handle? _____
Had the saran wrap stick to itself? _____
Had clothes stick to each other when getting them out of the dryer (static cling)? _____
Gone down a slide and had your hair stick up? _____
These are all examples of ___________________.
Conductors and Insulators
A material through which a charge will not move easily is called an electric ____________.
A material that allows charges to move about easily is called an electric ___________.
Metals are good conductors because at least one electron on each atom can be removed
easily. These electrons move ___________ throughout the piece of metal.
Good Conductors
Good Insulators
Under certain conditions, charges move through air as if it were a _________________.
The spark that jumps between your finger and a doorknob after you have rubbed your feet
on a carpet discharges you. In other words, you have become ______________ because
the excess charges have left you.
Similarly, lightning discharges a thundercloud. In both of these cases, air became a
conductor for a brief moment. Excess charges in the cloud and on the ground are great
enough to remove _________________ from the molecules in the air.
Chapter 20, Section 2 – Electrostatic Force
Main Idea - Forces between charged particles are mathematically related to charge and
distance.
Forces on Charged Objects
The electrostatic force can be demonstrated by suspending a charged rod so that it turns
easily.
The results of these experiments and the actions of the charged rods can be summarized
in the following way:
There are two kinds of electric charge: ____________ and ____________
Charges exert forces on other charges at a _______________.
The force is stronger when the charges are _____________ together.
Like charges _______________; opposite charges ________________.
Electric Force
When two charged objects are brought close together, they may experience motion either
_______________________________ from each other.
The closer the two objects are to each other, the ________________ the force
between them.
The _________________ the magnitude of the charges the stronger the force between
them
Applications of Electrostatic Forces
There are many applications of electric forces on particles
Used to collect soot in smokestacks, thereby reducing ______________________
Tiny paint droplets, charged by __________________, can be used to paint automobiles
and other objects uniformly
Photocopy machines use _________________________ to place black toner on a page to
make a copy
Coulomb’s Law
According to Coulomb’s Law, the magnitude of the force between two point charges (qa and
qb) a distance r apart can be written as follows.
FK
qa  qb
r2
The electric force, like all other forces, is a _________________ quantity.
The standard unit for Charge is called the ________________ (____).
The symbol for charge is _______.
One coulomb is the charge of 6.24 x 1018 electrons or protons.
The charge on a single electron is -1.60 x 10-19 C.
The magnitude of the charge of an electron is called the ___________________.
The charge on a single proton is +1.60 x 10-19 C.
Coulomb’s Law is used to calculate the force between 2 charged objects
FK
qa  qb
r2
Coulomb’s Constant, Kc = 9.0 X 109 N.m2/C2
qa and qb = Charge on object 1 and 2
d = distance between the objects.
F = Electric Force
Example – Coulomb’s Law
What is the magnitude of the electric force between a proton and an electron in a
hydrogen atom? The two particles are separated by a distance of 5.3 x 10-11 m on
average.
Given:
qa = -1.60 x 10-19 C.
qb = 1.60 x 10-19 C.
r = 5.3 x 10-11 m
Unknown:
F=?
Equation:
FK
qa  qb
r2
Chapter 22, Section 1 – Current and Circuits Electric current  Symbol = _______  Definition: __________________________________________________  Current is measured in __________________(__)  1 Ampere = _____________________________________  Types of Current o Direct current (DC): Motion of charges _______________________________________  Ex: __________________________ o Alternating current (AC) : Motion of charges ___________________________________ __________________________________________________  Ex: __________________________ Voltage 
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
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______________________________________________ is called the voltage (V). It is measured in _______________________________________ Voltage is also referred to as ______________________________ In order for current to flow, there must be ___________________________________ Batteries convert _____________________________ to _____________________________, which can be used to provide ____________________________________ The symbol for a battery is Resistance  Resistance (Symbol = ___) is _______________________________________________________  Resistance is measured in ________________________  The symbol for a resistor is  Resistance depends on o ____________________________________________________________ o ____________________________________________________________ o ____________________________________________________________ o ____________________________________________________________ Ohm’s Law Ohm's law states that ____________________(__) flowing in a circuit is directly proportional to the ____________________(__) and inversely proportional to the resistance (R). V
I
R
Sample Problem #1 (#9 on worksheet) If the power source is set at 6V and R is 2 ohms. What is the current? Sample Problem #2 (#11 on worksheet) If the current in the circuit is 7 amps and the resistance is 2 ohms, what is the voltage? Electric Power  Power is _____________________________________________________________________  Units for Power are _______________(__)  Since Power (P) is defined as energy transferred (or work done) per unit of time P= W/T o If I solve this for work (or energy), I get Work (or energy) = power x time  Electric companies measure and sell energy in _________________________ (______)  Formula for Electric Power P = V • I P = ______________ V = ______________ I = ______________ Power dissipated by a resistor  Resistors can be used to ____________________________________________________  The power dissipated by a resistor can be determined by ___________________________ ____________________________________________________ Example Problem  If the potential difference across an electric motor is 750 V and the resistance is 0.5Ω, how much power is needed? Two step method: One step method: