SHS3 Physics · Semester 2 Week 2: Direct Current

Lesson notes

Learning Objectives

Indicator: 3.3.1.LI.3 - Discuss how a galvanometer can be adapted as an ammeter and a voltmeter

By the end of the lesson, learners can:

Recall the structure and working principle of a galvanometer, including its key limitation of measuring only very small currents.
Explain why a galvanometer must be modified with a shunt resistor to function as an ammeter and with a multiplier resistor to function as a voltmeter.
Calculate the value of the shunt resistor required to convert a given galvanometer into an ammeter of a specified range.
Calculate the value of the multiplier resistor required to convert a given galvanometer into a voltmeter of a specified range.
Design a simple circuit using a milliammeter (galvanometer), resistor, connecting wires and a DC source that limits current to ten milliamperes, demonstrating the practical adaptation of the instrument.

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Curriculum details

Strand: Electric Field, Magnetic Field and Electronics (Strand 3)
Sub-strand: Direct Current (3.1)
Content standard: 3.3.1.CS.3 - Demonstrate knowledge and understanding of Kirchhoff's laws of electrical network. 3.3.1.LO.3 Explain the Kirchhoff's laws and applications.
Indicator: 3.3.1.LI.3 - Discuss how a galvanometer can be adapted as an ammeter and a voltmeter
Suggested placement: Semester 2, Week 2 (Week 22 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. 175

Exemplars (from the NaCCA curriculum)

Experiential learning: Provide learners with milliammeter, resistor, connecting wire and a dc source. Let learners design a circuit that will allow only ten milliamperes of current to pass through the galvanometer.
Provide equitable access to resources and opportunities.
Assessment (3.3.1.AS.3). The document marks these depth-of-knowledge levels for this indicator: Level 1 Recall; Level 3 Strategic reasoning; Level 4 Extended critical thinking and reasoning.
Teaching and Learning Resources:
- Audio-visuals
- Internet
- Projectors
- YouTube
- Interactive laboratory
- Connecting virtual wires
- Ammeter
- Galvanometer
- Voltmeter
- Resistance
- Rheostats
- Standard box resistors