Transcript Electric Charges & Current

AS A GROUP
What is electricity made of?
How can electricity have potential?
CTRIC CHARGES AND
CURRENT
ELECTRICAL POTENTIAL
Electricity has potential:
 This energy comes from the charge particle has due to its position in an electric field.
 Because like charges repel, it takes energy to push a charged particle closer to
another particle with a like charge. That energy is stored as the electric potential
energy. These particles can move and want to/will when it is free to move.
ELECTRIC CURRENT
Electrical devices need a steady flow of
electricity. The steady flow of charged
particles is called electrical current. The
flow continues until the energy source is
used up, or disconnected.
Electrical Current is measured in Amperes
CONDUCTORS
Allow the easy flow of electricity, loosely bound
electrons that are free to move from atom to atom
metals like aluminum, gold, copper and silver are
examples of good conductors.
INSULATORS
Insulators – resists the flow of electrons making
the object safe to handle
plastic, rubber, glass
Keep charges away from body
RESISTORS
Resistors-allow electrons to flow but slow them
down considerably. This allows the current to slow
down.
CURRENT ELECTRICITY: THE
CONTROLLED FLOW OF ELECTRONS THROUGH
A CONDUCTOR
electron movement in an insulator
electron movement in a conductor
LG: to understand the basics of current electricity
VOLTAGE
Voltage – causes current to flow through an electrical circuit
Volt – unit of measure to measure this potential
A Voltage Source (battery or generator) is required to maintain the
electrical potential in a circuit.
ELECTRICAL RESISTANCE
the opposition to the flow of electricity –
measured in Ohms – symbol is the Greek letter
Omega –
Electricity will take the path of least resistance
Ex: Lightning Rod
The greater the resistance, the less current there
is for a given voltage.
a. Longer wires have greater resistance than
short wires
b. Thin wires have more resistance than thick
wire
c. High conductors have less resistance than
insulators
SUPERCONDUCTORS
There are some materials that have practically no
resistance at extremely low temperatures. These
are called Superconductors. Superconductors have
many uses including use in power lines to increase
efficiency as well as in computers to improve
speed.
GROUNDING
As discussed charges/electricity likes to move
through lines with lower resistance. Because of this
we have developed a procedure known as
grounding. Grounding means providing a
harmless, low-resistance path-a ground- for
electricity to flow.
This is used to protect buildings from damage
from lightning strikes.
A “Lighting Rod” moves lighting strikes into the
ground where the charge is absorbed.
OHMS LAW
Ohm’s Law explains the relationship
between voltage (V or E), current (I) and
resistance (R)
Used by electricians, automotive
technicians, stereo installers
It is the push or pressure behind current
flow through a circuit, and is measured in
(V) volts.
Current refers to the quantity/volume of
electrical flow. Measured in Amps (A)
Resistance to the flow of the current.
Measured in Ohms
1. Assuming the resistance does not change:
As voltage increases, current increases.
as voltage decreases, current decreases.
2. Assuming the voltage does not change:
As resistance increases, current decreases.
As resistance decreases, current increases.
CHAPTER 5 QUESTIONS
1) What is the difference between resistance and insulation?
2) Describe some of the disadvantages of solar cells listed from your
book.
3) How can a lightning rod protect a building from fire? Describe why
lightning strikes it rather than something else.
4) How do rechargeable batteries work differently from
nonrechargeable ones?
5) Describe how we can increase or decrease electrical potential
energy.
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