Framework Physics 12
An Inquiry Based Science Teaching and Learning Framework
Topic/Learning Activity
Investigating electronics.
OP57/OP58/OP59/OP60
Student Cohort
Student Level
Second Year Final Term
P12
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Prior Knowledge
Familiarity with symbols for electrical devices e.g. battery, switch, ammeter, voltmeter and digital
multimeter (DMM); a knowledge of current, voltage and a.c./d.c. Some knowledge of atomic number
(and electronic arrangement).
Stimulus to Engage
How do you get the students interested in the topic to start?
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State whether a.c. or d.c. is required to power devices such as: a hand torch, a camera, an iPod, a
hand-held radio, a washing machine, etc. etc.
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List electrical/electronic devices now available that parents/grandparents did not have access to
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Name some components that are contained in a specific device
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Describe the physical appearance of the very first computer (desktop) that you saw
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Describe the physical appearance of the most modern computer that you have encountered
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Identify some differences between the ‘old’ and the ‘new’ types of computer. Would someone
volunteer to resource photos of a variety of computer types and display them in the laboratory for
the next class?
Science Questions
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With reference to the Periodic Table of the Elements (PTE), name the element that is most widely
used in electronics today
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Can you name any device that contains this element?
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What is the function of the human heart?
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Does blood flow to and fro in the body? Explain
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What device is used by plumbers in water systems to ensure that water flows only in one direction?
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Can a.c. be converted to d.c? How might this be achieved?
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Does a diode conduct current?
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Does a LED conduct current?
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Explain what is meant by a ‘light dependent resistor’
Learning Outcomes
Content Knowledge:
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Compare diode and LED; discuss the operation of the circuits; interpret results; draw conclusions
from observations; recognise the possibilities for each component in a variety of situations/circuits;
demonstrate that the resistance of a LDR can easily be changed
Framework Physics 12
An Inquiry Based Science Teaching and Learning Framework
Process:
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Safety issues; show operational circuits for all three components: use the
software in conjunction with the sensor technology; modify the circuits or
adapt them for other use
Apparatus supplied: Diode, LED, LDR, 560Ω resistors, connecting wires,
crocodile clips, 6V filament bulb + holder, 6V battery, digital multimeter (DMM)
Skills:
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Team work, manual dexterity, thinking and reasoning
P12
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Questions during Activity
Questions to drive student learning (directing them to the learning outcomes)
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Is the sequence of components in the circuit important?
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Has each component in the circuit got a positive and a negative terminal i.e. has the device got a
‘polarity’?
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How do you know if a diode is conducting?
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How do you know if a LED is conducting?
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How do you change the resistance of an LDR?
Questions to probe understanding:
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Explain what the symbols for a diode, for a LED and for an LDR, are meant to convey
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Examine each component closely - do you notice any differences between the connecting ends
If so, of what significance are they?
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Referring back to the heart and the plumber/water flow questions, what does a diode do in an
electrical circuit?
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Give some advantages of a LED over a filament bulb
Questions to get students thinking about their own learning (metacognition):
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How might a diode, LED and LDR be connected in a circuit using a 6V battery so that the LED
lights?
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Draw a simple circuit that could be constructed so that a buzzer or bell sounds at dawn
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A battery, resistor and LED are arranged in a circuit so that the LED is lighting brightly. How might
a second LED be connected to the circuit so that both LEDs light brightly?
Developing the Activity
How do you stimulate students to ask even more questions/think further?
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List situations where you see LED’s in operation and explain why they are used in preference to
filament lamps
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What common property does a diode share with a LED?
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Identify a use that the ESB might make of an LDR
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If you had a bulb lighting in the attic to prevent water pipes freezing, how might a LDR be used to
alert you of bulb failure?
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Framework Physics 12
An Inquiry Based Science Teaching and Learning Framework
Possible supporting activities:
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Construct (using soldering techniques) a simple circuit using a LED that
could be used to test for continuity in fuses and filament lamps, etc.
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Research the operation of a one-way valve system as used in plumbing
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Use internet to investigate use of LEDs in traffic lights and car brake lights
Questions for supporting activities:
P12
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List as many situations as possible where any one of the three components
(diode, LED, LDR) might be used in everyday life
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Research the uses and advantages of LEDs. In what colours are they available?
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Explain how/why a diode might be incorporated in a device as a safety precaution
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Reflecting Back to Learning Outcomes:
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How many of your intended outcomes were achieved?
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Do any of your intended outcomes need to be revised?
Additional Resources
Some demonstrations are useful but, ideally, practical work by the students is invaluable when dealing
with this component of the syllabus.
Observation skills are honed by suggesting that students be alert while travelling home from school and
they identify situations/locations where these electronic components might be used.
Internet sites such as: www.howstuffworks.com › ... › Solid State Electronics
How has the use of ICT enhanced the learning?
A current sensor definitively convinces the student when the diode (and LED and LDR) is conducting
or not. Of equal importance, a voltage sensor allows the student to observe that the voltage across a
diode (and also a LED) remains fairly constant when they are conducting. The voltage sensor across a
LDR in a circuit records a change in voltage as light falls on the LDR - leading to the conclusion that the
resistance is changing.
Evidence of enhancement:
Students have commented on the small magnitude of the currents involved as opposed to current
size involved in earlier circuits e.g. the filament lamp. Also, students appeared more confident when
discussing a.c. and d.c.
Students were subsequently more comfortable in interpreting graphical representations involving
current, voltage and time.
Students were alert to the differing connections for current and voltage sensors.
Additional Comments
Practical investigative work in the electronics area is always enthusiastically undertaken by students,
especially when (peripheral) work results in the construction of a useful circuit that the student can
understand and has a use for, e.g. a continuity tester.
The three components investigated have applications in a wide variety of devices and so students had
no difficulty in identifying applications and uses.
This group of students responded well to the challenges involved. With hindsight, maybe the topic might
be more generally suitable for the first term in Junior Cert year.