Analogue Electronics · SHS1 Physics

Lesson notes

Learning Objectives

Indicator: 1.3.3.LI.2 - Explain the effect of temperature changes on resistance using a thermistor, light-dependent resistor (LDR), infra-red diode and the microphone and analyse the characteristic graphs of thermistors and LDRs.

By the end of the lesson, learners can:

Explain how the resistance of a thermistor changes with temperature and distinguish between negative temperature coefficient (NTC) and positive temperature coefficient (PTC) thermistors.
Explain how the resistance of a light-dependent resistor (LDR) changes with light intensity.
Describe the effect of temperature or heat on the behaviour of an infra-red diode and a microphone in a simple circuit.
Analyse and interpret the characteristic resistance-temperature graph of a thermistor and the resistance-illumination graph of an LDR.
Apply the concepts of thermistors and LDRs to suggest practical uses in everyday devices found in Ghana.

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Curriculum details

Strand: Electric Field, Magnetic Field and Electronics (Strand 3)
Sub-strand: Analogue Electronics (3.3)
Content standard: 1.3.3.CS.2 - Demonstrate knowledge and understanding of the Input and Output processes of a Transducer 1.3.3.LO.2 Distinguish between input and output of transducers and show their applications in thermistors, light dependent resistors, infra-red diodes, microphones, buzzers, loudspeakers and electromechanical relays.
Indicator: 1.3.3.LI.2 - Explain the effect of temperature changes on resistance using a thermistor, light- dependent resistor (LDR), infra-red diode and the microphone and analyse the characteristic graphs of thermistors and LDRs.
Suggested placement: Semester 2, Week 13 (Week 33 of the year)
Our suggestion, laid out in curriculum order across three terms of twelve weeks. NaCCA does not fix the week, so follow your school's scheme of learning.
Curriculum reference: NaCCA curriculum document, p. 74

Exemplars (from the NaCCA curriculum)

Experiential Learning: Using simulation or laboratory set up or science kit, learners in groups of mixed abilities investigate the effect of temperature changes on resistors in some applications.
Ensure that the teaching materials, examples, and illustrations reflect diverse perspectives.
Assessment (1.3.3.AS.2). The document marks these depth-of-knowledge levels for this indicator: Level 2 Skills of conceptual understanding.
Teaching and Learning Resources:
- Videos
- Interactive simulations
- Flash cards