Download Ch 10

Ch 10
10.1 The Electric Circuit Lab
Lab
10.2 Electricity and Electric Circuits
Outcome 308-16, 308-15
Electric current – the movement or flow of electric charges from one place to another.
Electric circuit – a controlled path through which electric current passes.
Static electricity
An electric charge that
remains in a fixed position
or region on an object
Vs
Current electricity
Is an electric charge that is
moving on one or more
paths. The movement of
electric charge is electric
current.
Parts of an Electric Circuit
1. Source of electrical energy
photoelectric cells - calculator – tiny amounts of energy
cells/batteries
portable generators – job site – medium amount of energy
wall outlets
- medium amount of energy
Nuclear power plant – huge amounts of energy
2. Electrical load
-anything that converts electrical energy into what ever form of energy we need
light bulb, toaster, motor,
3. Electric Circuit Control Device
light switch, on/off buttons, timers
4. Connectors
- a conducting wire that provides a controlled path for electric current to flow to each part
of the circuit
Can be a few atoms wide, or the power lines you see
Closed circuit - a circuit that is operating and through which current is flowing. (all parts of the
path are attached)
Open circuit – a circuit that is not operating and through which no current is flowing. (part of the
path is not attached)
Schematic circuit diagrams – pg 545 – drawings using a special set of symbols to draw electric
circuit.
10.3 Electrical Potential
308-18
Electrical potential – The electric energy that an electron possesses
Voltage – electric potential – the electric energy that an electron possesses
SI – The International System of Units (abbreviated SI from the French Le Système
International d'Unités) is the modern form of the metric system and is generally a system
devised around the convenience of the number 10. It is the world's most widely used system of
units, both in everyday commerce and in science.
Volt – the SI unit used to measure electric potential/voltage; symbol V
Read – special attention to Table 1
Career Profile
10.6
208-1,209-3, 210-10, 210-7
Lab
10.7
9-V battery – 6 Dry cells
6-volt battery – 8 Dry cells
1.5 volt battery – 1 dry cell
These use series circuits and parallel circuits
Cells in Series
Series Circuit – an electric circuit in which the electrical loads are wired to one another in a
signal path




The electric potential of a single electron in a dry cell has a maximum of just under 2
volts.
By connecting cells together in a series we can get much higher voltages.
An electron goes through 1 battery and goes through a chemical reaction and gains 1.5
Volts.
If another battery is hooked up In series (positive end to negative end) the 1.5 volt
electron goes through another chemical reaction and gains another 1.5 volts, for a total
charge of 3 volts.
Cells in Parallel
Parallel Circuit, - An electric circuit in which each electrical load is connected to the energy
source by its own separate path.


If 2 cells are connected in parallel (positive end to positive end, negative end to
negative end) twice as many electrons are available.
Each electron will only have the electrical potential gained from 1 battery (cell)
Series
Note: Positive end connected to
negative end, and positive end
connected to negative end, and etc.
Parallel
Note: Positive end connected to
positive end, connected to positive
end, and negative end connected to
negative end, connected to negative
end
10.8
Read
Voltage, Current, Resistance Lab - Handout
10.10
Read
Resistance – the ability to impede the flow of electrons in conductors
Ohms – the SI unit for electrical resistance; Ω
V=IxR
Voltage drop = Current x Resistance
V=AxΩ
Short Circuit – Positive and negative terminal of a dry cell are connected with no load to use the
energy as the electrons become more and more charged. The short circuit may heat up enough to
cause a fire.
10.13
Loads in series
If you have a circuit with 3 light bulbs in a row they are in series.
There is only one path.
If one part of the circuit in interrupted nothing will work
The more bulbs you add the more the resistance
The more the resistance the lower the current
Loads in Parallel
If you have a circuit with 3 light bulbs each connecting to the power source they are in parallel.
There more than one path.
If one part of the circuit in interrupted the other parts will still work
The more bulbs the more the current