Transcript SNC 1D circuits

Electric Circuits
Voltaic Cells

A source of energy that generates an
electric current by chemical reactions
involving two different metals or metal
compounds separated by a solution that is a
conductor.
 A battery is a connection of two or more
cells
 A voltaic cell has two metal terminals called
electrodes that are made of different metals
with different abilities to hold onto electrons.
 Electrodes are in a conducting paste called
electrolyte.
Types of cells…
Primary Cell : cannot be recharged
e.g. Zn-C cell
Secondary Cell :
rechargeable
e.g. car battery
Wet Cell: electrolyte is a solution.
e.g. car battery
Dry Cell: electrolyte is a moist paste.
e.g. Zn-C cell
DON’T throw me in
the garbage . . .
take me to the
landfill instead!
Fuel Cell
A cell that generates electricity through
the chemical reactions of fuel that is
stored outside the cell.
 Example: hydrogen fuel cell combines
hydrogen that is stored in a tank with
oxygen from the air. The only byproducts are heat and water.

Solar Cells
A cell that converts sunlight into
electrical energy.
 Renewable energy

Current Electricity
Is made up of moving electrons flowing through a
suitable conductor.

Parts of an Electric Circuit
1. Source: provides electrical energy to the rest
of the circuit. Example: battery
2. Load: converts electrical energy into other
forms of energy. Example: toaster
3. Conductor: provides a pathway for electrons
to flow.
4. Control: controls the flow of electrons.
Example: switch or fuse.
You Try It!!

P. 445 # 2-5, 8
Open Circuit
A circuit that has a gap or a break.
 Electrons do not flow through
 A circuit is open when the switch is
open

Movement of Electrons
Electrons flow in one direction through
the circuit
 Electric Current: the rate of movement
of electric charge; the flow of
electrons.

 Example:
river current
The electric charge passing by a point
in a circuit is measured in large
numbers of electrons. The unit of
electric charge is the coulomb.
 1 coulomb = 6.25 X 1018

Amperes
Unit for electrical current is called the
ampere (A)
 1 A in a circuit means that 1 C
(coulomb) passes a given point in a
circuit every second.
 Measured using an ammeter

Electrical Resistance
The property of a substance that slows
electric current and converts electrical
energy to other forms of energy.
 In many circuits a resistor is used to
decrease the electric current through a
part of the circuit.

Loads
Resistors or any other device that
transforms electrical energy into heat,
motion, sound or light.
 Example: lightbulb, fan, speakers.
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Voltage
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Voltage is also known as potential
difference
It is the value that relates to the amount of
work that is done on each coulomb.
Measured in volts
Volt = 1 joule (j) per coulomb (C)
Potential difference is the difference
between the electric potential energy per
unit of charge at two points in a circuit.
Measured with a voltmeter
You Try it!!!

P.454 # 1, 2, 4, 7