Download Electric Charge and

KEY
Electric Charge and
Static Electricity (Section 17-1)
1. All matter is composed of very small particles called ATOMS. The center of an atom is called the
NUCLEUS and is composed of positively charged particles called PROTONS and particles that don’t
have a charge (neutral) called NEUTRONS. Outside the nucleus is an electron cloud with negatively
charged particles called ELECTRONS.
2. The Law of Electric Charges states that like charges REPEL and unlike charges ATTRACT. The
force between the charged particles is called the electric force and it depends on the SIZE of the
charge and the DISTANCE between the charges.
3. Usually an atom is neutral because the number of positive PROTONS equals the number of
negative ELECTRONS.
4. Atoms can become charged because they GAIN or GIVE AWAY the negative ELECTRONS.
5. There are three methods of charging an atom (moving the electrons):
a. FRICTION- rubbing two objects together causing one object to transfer electrons to the
other object
b. CONDUCTION - transferring the electrons from one object to another by direct contact
c. INDUCTION - an uncharged object has the particles of the atoms inside it rearrange due to
the attraction or repulsion of the particles of a charged object
6. Which method above explains why plastic wrap clings to a container? Explain your answer.
INDUCTION – bowl or container isn’t charged, but wrap became charged by friction
7. You can determine if an object has a charge by a device called an ELECTROSCOPE.
Word
Electricity
*BrainPop
Static electricity
*BrainPop
Explanation
Drawing / Example
The movement of ELECTRONS, negatively
charged particles
The build-up of ELECTRIC CHARGES that
can be discharged rapidly
By friction, conduction, or
induction
Ex: shuffle across floor
Ex: metals / water
Conductor
Materials that ( do / do not ) transfer electric
current well
Insulator
Materials that ( do / do not ) transfer electric
current well
Ex: plastic, wood, air,
rubber, glass
Ex: silicon
Semiconductor
Materials that are in-between a conductor and an
insulator
Word
Diode
(di = 2, so these
are 2 pronged!)
Chapter 19,
Section 1
Transistor
Electric / Static
Discharge
Explanation
A semiconductor device that acts like a one way
valve to control the flow of electricity in
electrical circuits.
*Solar cells produce DC when light strikes them.
*LED (light emitting diodes) emit visible light or
infrared radiation when CURRENT passes
through them
Drawing / Example
Ex: a TV remote control
or the lighting behind the
screen in an LED TV or
notebook computer screen.
A SEMICONDUCTOR device made from
silicon that is used to amplify electrical signals
(in stereos or radios) or to act like a light switch
turning the flow of electricity on and off.
Ex: lightening rods on
The rapid transfer of ELECTRIC CHARGE and bridges or tall buildings
is explained by a "shock"
Electrical Energy (Section 17-2)
1. One way to produce an electric charge is through a CELL which is a device that produces an
electric current by converting CHEMICAL energy into ELECTRICAL energy. Put cells together to
make a BATTERY.
2. WET cells have liquid electrolytes (acids) such as the cells in a CAR battery.
3. DRY cells have solid or paste like powders such as the cells you use in RADIOS / CELL
PHONES.
4. In order for an electric current (flow of electric charges) to be produced by a cell, there must be a
difference between the electrodes (the ends). This difference is called POTENTIAL DIFFERENCE
(also called voltage) and is measured in VOLTS ( V - abbreviation).
5. So, what do we mean by a "dead" cell/battery? NO LONGER HAS POTENTIAL
DIFFERENCE AND ALL THE CHEMICAL ENERGY TO ELECTRICAL ENERGY HAS
OCCURRED.
Electric Current (Section 17-3)
Name _____________________________
Word
Explanation
Current
(C.I.A.)
*BrainPop
The RATE at which charges pass a given point.
More charges = more current
Amperes (amps
= A)
Unit for CURRENT.
More current = increased A
Direct Current
(DC)
The charges flow IN THE SAME
DIRECTION. Produced by CELLS and
BATTERIES
Alternating
Current (AC)
The charges switch from flowing in one
direction to the reverse.
Drawing / Example
Shown as an “I” in formulas
– CIA = Current, shown as I,
measured in A (amps)
Used in our HOMES
Voltage /
potential
difference
(how much
"push")
Resistance (R)
The difference in energy per unit charge as a
charge moves between two points in a path of a
current
120 V for most household appliances, but 220V
for ELECTRIC OVEN or the ELECTRIC
DRYER
The opposition to the flow of ELECTRIC
CHARGE.
Good conductors have LOW resistance and
insulators have a HIGH resistance.
Formula Triangle:
Ohms
Ω
Measurement unit for Resistance.
I = V / R or V = I x R
Formula Triangle:
Electric Power
P=VxI
The rate at which ELECTRIC current is used
to do work.
*the more power = more
friction = more TE
Less Resistance -( smaller / larger ) wires / ( shorter / longer ) wires / ( lower / higher ) temperatures
Higher Resistance - ( smaller / larger ) wires / ( shorter / longer ) wires /
( lower / higher ) temperatures (too many things moving fast to get in the
way)
Electric Circuits (Section 17-4)
Word
Circuit
Load
Series circuit
Parallel circuit
Circuit Overload
Name _________________________________
Explanation
A CLOSED path electric charges flow
through
Opened/Closed using a SWITCH
Open circuit = on or off
Closed circuit = on or off
Drawing /
Example
Circuit means to
“go around”
A device that uses ELECTRICAL energy
to do work
Ex: lights,
appliances,
computers
All parts are connected in a SINGLE loop
and the charge can only follow ONE path.
The loads/devices share the same
CURRENT, so if you add loads the current
DECREASES.
If one load/device is off or doesn't work, the
whole circuit WON’T WORK.
Good uses of
series circuits:
Power strip,
automatic door @
store, alarm
system, room
buzzer
All the loads/devices are located on separate
BRANCHES of the circuit and there are
different paths for the electric charges to
travel. The loads/devices do not share the
same CURRENT. If one load/device is off
or doesn't work, the whole circuit WILL
CONTINUE TO WORK. (receive same
voltage)
Too many loads/devices are connected in
the CIRCUIT and there are too many
electric CHARGES flowing. This causes
the temperature to increase and may cause a
fire.
Good uses of
parallel circuits:
electrical circuits
in our
homes/offices
Safety: fuses / circuit breaker box
+Revisit transistor w/ transformer
*Ex: Hair dryer
and lamp on same
circuit, so they
have to share the
current… dryer
takes increased
current and lamp
takes less current
and this can
overload the
circuit