- Slides: 29
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 electrons
�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!
Electron movement e-
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 switches
Moving Electrons can be changed to many other desired forms… �Kinetic (movement), light, sound, heat
Example: There is more current running through a toaster (13. 6 A) than a wristwatch (0. 00013 A).
Measured in Amperes… �SI unit for current is ampere, (A) �Symbol for ampere is I �Slightly less than 1 A runs through a 100 W lamp connected to a 120 V circuit �Measured using an ammeter �Equivalent to the current in a river
Moving Electrons… Current= rate of electron movement
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. 25 X 10 18 electrons �Time is measured in seconds
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)
Example 1: 1. What is the current through a circuit with 3 coulombs of charge in 10 sec? G: Q= 3 C, t=10 s R: I =? A: I= Q/t = 3 C/10 s S: I= 0. 3 A S: Therfore, there is 0. 3 A of current flowing through the circuit
Example 2: 2. What is the charge within a circuit that has 6 A of current over 3 seconds? G: I= 6 A, t=3 s R: Q =? A: I= Q/t Q= It S: Q= 18 C S: Therfore, there are 18 coulombs of charge flowing through the circuit
Example 3 3. How much time will it take for 12 C of charge to pass through a circuit with 5 A of current? G: Q= 12 C, I= 5 A R: t= ? A: I = Q/t t = Q/I t = 12 C/5 A S: t = 2. 4 s S: Therfore, it will take 2. 4 s
Electric Shock �Feel it at. 001 A (tingling at 0. 002) �“let go threshold” (0. 016 A convulse); can’t breathe �Usually fatal at 0. 05 A (heart stops, fibrillates) � 0. 833 A- amount needed to light a 100 -W lamp
The body closes the circuit… �Muscles automatically contract until flow stops
Can cause severe burns at exit points…
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 ambulance
�Don’t touch the victim. You might get a shock, too! �Disengage the victim from the electric current by �cutting the power at the source or �using a nonconductive object to free the victim from the energy source without touching him or her directly.
�A raccoon suffered an 11, 000 volt electric shock when it scampered up a pylon in Cyprus but escaped with burns.
F 1: BMW mechanic receives electric shock at Jerez
Electroshock fishing… �Survey Streams /content without killing
Electroshock therapy. . .
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?