Electric Current RECALL In static electricity an electric charge stays in one area In current electricity an electric charge moves through conductors along a path Its electrons that move NOT ID: 717495
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Slide1
Current Electricity
Page 314: 10.9Slide2
Electric Current:
RECALL: In static electricity, an electric charge
stays
in one area.
In current electricity an electric charge moves through conductors along a path
Its
electrons
that move NOT
protons
!
A cell, battery or a direct current from a wall plug provide the energy to push electronsSlide3
Current electricity is generated and used as a source of energy in homes and industry.
Current electricity is a flow of
electrons,
usually through a
CONDUCTOR.
In all dry
CELLS,
the flow
of ELECTRONS moves from negative to POSITIVE.
The electrons flow
in ONE direction ONLY!Slide4
Electron movement
e-Slide5
Electric Circuit
Electric circuit: a closed controlled path for charges to move.
All circuits contain at least 3 of the following parts:
Source of Electrical Energy: a power source such as a battery or a wall outlet
Electrical Load: something that converts electrical energy into another form. Loads are the reason the circuit exists in the first place. Ex. Light bulb or a toaster.
Connectors: A conducting wire that allow the charges to move from the power source to the load.
Electric Circuit Control device: these are switches that can stop the flow of charges in the circuit. Ex. A light switch or a timer on a microwave ***NOT all circuits contain switchesSlide6
Moving Electrons can be changed to many other desired forms…
Kinetic (movement), light, sound, heatSlide7
Current
Current is the amount of electrical
charge
MOVING
from one place to another. (The amount of electrons moving)
Current
is represented by the symbol, I and is measured in amperes (amps or A) with an
AMMETER
.Slide8
Example: There is more current running through a toaster (13.6 A) than a wristwatch (0.00013A).Slide9
Measured in Amperes…
SI unit for current is ampere, (A)
Symbol for ampere is I
Slightly less than 1A runs through a 100W lamp connected to a 120V circuit
Measured using an ammeter
Equivalent to the current in a riverSlide10
Moving Electrons…
Current= rate of electron
movementSlide11
What makes up Current?
Current is the charge moving past a point in a conducting wire every second. Therefore the number of coulombs/second = current.
WHAT IS CHARGE????
CHARGE is measured in COULOMBS
1 coulomb of charge = the charge on 6.25X10
18
electrons
Time is measured in secondsSlide12
FORMULA
WHERE:
I is the current measured in Amperes (A)
Q is the charge measured in coulombs (C)
t
is the time measured in seconds (s) Slide13
Example 1:
1. What is the current through a circuit with 3 coulombs of charge in 10sec?
G: Q= 3C, t=10s
R: I =?
A: I= Q/t
= 3C/10s
S: I= 0.3 A
S:
Therfore
, there is 0.3A of current flowing through the circuit
Slide14
Example 2:
2. What is the charge within a circuit that has 6 A of current over 3 seconds?
G:
I= 6A, t=3s
R:
Q
=?
A:
I
= Q/t
Q= It
S:
Q= 18 C
S:
Therfore
, there
are 18 coulombs of charge flowing
through the circuit
Slide15
Example 3
3. How much time will it take for 12C of charge to pass through a circuit with 5 A of current?
G: Q=
12C
,
I= 5A
R:
t= ?
A:
I = Q/t
t = Q/I
t = 12C/5A
S: t = 2.4 s
S:
Therfore
,
it will take 2.4s Slide16
Voltage
Voltage
is the force that moves electric charges in a circuit. Makes the currents flow. Measured in volts (V) by a
VOLTMETER
.
Ex
. Batteries can be stronger or weaker depending on their voltage. A 9V battery provides more force than a 6V batterySlide17
Resistance
Resistance
is the ability that tries to stop or slow down the
electric charges
in a circuit.
Measured in
OHMS
by an Ohmmeter
.
= ohms
Example
: a light bulb in a
circuit creates resistance as the electrons slow down and create so much heat the light bulb glowsSlide18
Electric Shock
Feel it at .001 A (tingling at 0.002)
“
let go threshold
” (0.016A convulse
)
;
can’t breathe
Usually fatal at 0.05A (heart stops, fibrillates)
0.833A- amount needed to light a 100-W lampSlide19
The body closes the circuit…
Muscles automatically contract until flow stopsSlide20
Can cause severe burns at exit points…Slide21Slide22
What to do if the victim…
loses consciousness;
is thrown by the shock;
touched a voltage source of more than 600 V;
has burn marks on skin at points of contact with current. Generally, the only outward sign of internal burns is electrical marks at the contact points. Internal damage may thus be much more serious than the external injuries suggest.
Call an ambulanceSlide23
Don’t touch the victim. You might get a shock, too!
Disengage the victim from the electric current bycutting the power at the source
or
using a nonconductive object to free the victim from the energy source without touching him or her directly.Slide24Slide25
A raccoon suffered an 11,000 volt
electric shock when it scampered up a pylon in Cyprus but escaped with burns
.Slide26
F1: BMW mechanic receives electric shock at JerezSlide27
Electroshock fishing…
Survey Streams /content without killingSlide28
Electroshock therapy...Slide29
Questions:
1. What is current?What 2 things make up current and how do they affect the flow of electrons?
How is electricity converted to other forms of energy?
What 4 types of energy are electricity converted to?
Explain what to do when someone is receiving an electric shock?
What are some uses of electric shock?