It is expected that students will compare series and parallel circuits involving varying resistances, voltages, and currents.
Students who have fully met the prescribed learning outcome are able to:
Define resistance
Draw circuit diagrams using appropriate symbols that are
properly placed
Conduct experiments to:
- measure voltage and current, using appropriate
equipment and units (e.g., volts, amperes)
- determine resistance, using current and voltage data
Perform calculations using Ohm’s Law
For a fixed supply voltage, differentiate qualitatively between
series and parallel circuits in terms of:
- current (may change from resistor to resistor in parallel;
remains the same in series)
- voltage (may change from resistor to resistor in series;
remains the same in parallel)
- total resistance (increases with the number of resistors in
series; decreases in parallel)
photo: hotblack@morguefile
..................................................................................................................................................
RESOURCES:
Energy and Environment; Voltage; exercise to determine the relationship between voltage, amperage and resistance (Ohm's law)
Parallel and Series Bulbs - worksheets
Electricity and Magnetism, HyperPhysics, Georgia State University
This Interactive module will introduce you to many of the basic concepts involved with Electricity and Magnetism. We will introduce you to static charge, moving charge, voltage, resistance, and current. Magnetism and how it relates to electricity will also be presented.
...................................................................................................................................................
PLANNING FOR ASSESSMENT /ASSESSMENT STRATEGIES
Ask students “If power supplies give energy
and a voltage increase to charges, what are
devices called that take away energy?”
Students (in groups) will brainstorm and list
objects that take energy from a charge. They will
generalize and call them resistors. Their
observations and definition will be recorded in
their journals. Assess by considering how many
different devices students can come up with.
............................................................................................................................................
Display a circuit and show how the
corresponding circuit diagram is drawn,
using standard symbols to show power
supplies or cells connected in series, wires,
resistors, and voltmeters and ammeters
correctly connected.
Have students set up their own circuit following
the circuit diagram presented. Provide assistance
as required. Ask students to
- measure the voltage across a power supply
and current through it for at least five
different voltages and record the data. (they
can increase voltage by adding more cells in
series or changing the setting on the power
supply)
- determine the voltage-current ratio for each
trial and record data in their data table
If they are able, they should measure the
resistance of the resistor using an ohmmeter.
Have students examine their data to see what is
constant and draw conclusions. Assess whether
- they conduct the set up carefully
- provide accurate data and diagrams
- draw conclusions that correspond to the
substance of Ohm’s Law
Provide help with the activity and with concept
development as necessary.
................................................................................................................................................................
Review Ohm’s Law and units. Demonstrate
several examples of problems involving
Ohm’s Law and including unit prefixes such
as milli, mega and kilo.
Students complete Ohm’s Law problems and
submit for marking. Award marks for proper use
of units and showing work, as well as obtaining
correct results.
.......................................................................................................................................
Demonstrate for students
- 1, 2 and 3 resistors connected in series and
parallel (keep the terminal voltage
constant throughout)
- the proper use of voltmeters and
ammeters in these circuits (voltage and
current are measured in each circuit and
across each resistor and power supply)
• Have students, working in groups, draw
diagrams of each of the circuits demonstrated.
Have students record the terminal voltage, the
voltage across each resistor, and the current
through each resistor. Verify for accuracy.
• When assessing student work, look for their
ability to
- identify patterns in their data
- state what happens to current, and voltage in
the circuits and how they changed (or did not
change) in each series and parallel circuit
....................................................................................................................................................
Follow up by using Ohm’s Law to calculate
total resistance in the circuit using the
terminal voltage and the current readings
from the power supply.
• Students should recognize that
- in a series circuit, the total resistance has
increased as resistors have been added in
series
- in a parallel circuit resistance has decreased as
resistors have been added in parallel
......................................................................................................................................
