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SNC1P
Name: _______________
Date: ________________
12.8 & Chapter 13 - Circuits
12.8 - Moving Charges
Materials that are conductors of electricity allow electrons to move through them easily.
e.g., metals such as copper, aluminum, silver, gold, tap water (because of dissolved
minerals and ions)
Materials that are insulators resist or block the flow of electrons.
e..g, plastic, glass, rubber, air, wood
The ________________ of a substance is a measure of how well it conducts electricity.
We depend on electric current (the flow of electricity through a conductor in a ________________
path) to power our electrical devices. The electric current can come from:
-a battery (direct current)
-a power plant, through our electrical outlets (alternating current)
**Do questions #1-6 on page 488**
13.1 - What is an Electric Circuit?
An electric circuit is a ________________ path along which electrons flow. In a series circuit,
electrons only follow one path. In a parallel circuit, electrons can follow more than one path.
Part of a circuit:
Description:
load
electrical device that converts electrical
energy into another form of energy (e.g.,
a light bulb, fan, motor)
control device that allows you to safely
open or close a circuit
switch
Circuit diagram symbol:
open:
closed:
energy source
provides the electrical energy (e.g., a
battery)
conducting wire
allows electrons to flow easily through
the circuit
**Do questions #1,2,4,5 on page 503**
13.4 - Measurements in Electric Circuits
electric current (I)
potential difference or
voltage (V)
electrical resistance (R)
what it is:
measured by:
in what units?
the rate of flow of electrons past a
certain point in a circuit
the difference in electric potential
energy measured between two
points
the ability of a material to oppose
the flow of electrons through it
ammeter
amperes (A)
All materials have a certain amount of electrical resistance. The resistance depends on 4 main
factors:
-type of material (copper has ________________ resistance than carbon)
-length (the longer a wire, the ________________ electrical resistance it has)
-thickness (a thick wire has ________________ electrical resistance than a thin one)
-temperature (the higher the temperature, the ________________ the electrical resistance)
A multimeter can measure current, potential difference, and resistance.
**Do questions #1-5 on page 513**
13.7 - Factors Affecting Series Circuits
Ohm's law = the relationship between resistance, current, and potential difference: V = IR
-the higher the resistance (R), the less current (I) can flow
-the higher the potential difference (V), the more current (I) can flow
Factors that can increase the total amount of resistance in a series circuit:
-adding more ________________ in series (instead of in parallel)
-making the conducting wire longer or ________________
-changing the material of the conducting wire (metals such as silver, platinum, rhodium have
very low internal resistance)
Different batteries have different voltage rating. High voltage rating results in more current flowing.
**Do questions #1-6 on page 521**
13.8 - Safety Issues with Circuits
Electric shocks can result from poorly insulated wires, and if your skin is wet (with tap water), your
skin becomes a much better conductor.
Overloaded circuits in your home can overheat and cause a fire.
-as more loads are plugged into outlets (parallel circuits), it decreases ________________but
increases ________________, which can cause overheating and cause a fire
-circuit breakers are connected in series with switches and outlets in your home, and will open
if there is too much ________________flowing through a circuit
-older homes have ________________instead of circuit breakers
GFCI outlets in bathrooms automatically break the circuit if a change in current is detected.
**Do questions #1-6 on page 524**
13.9 - Thermal Energy in Circuits
Many electrical devices convert electrical energy to thermal energy for specific purposes.
-toasters have exposed heating elements which have high resistance and heat up as electrical
current flows through
-hair dryers, flat irons, and heaters use ceramics (that are combined with metals) that heat up
but current stops flowing once they reach a certain temperature
-electric blankets, clothing irons, and electric grills use heating elements that are sealed in
insulators such as plastic
**Do questions #1,2,4,6,7 on page 527**