Grade 9 · From USB to Field System: ESP32 water quality

Multimeter skills

Follow the student handout to build, test and document this stage of the water-quality system.

Prepared lesson material. Start this task when your teacher introduces it; it is not currently assigned homework.

For this lesson

Open student handout (Word)All Grade 9 handouts →

2 pages · Use the handout for the complete instructions, examples and response spaces.

Read the handout text online

For diagrams, visual examples and the full layout, open the handout above.

Lesson 2: Electrical Quantities and Multimeter Skills

Student practical and measurement record

Grade 9 MYP Design | From USB to Field System

Name: __________________

Class / team: __________________

Date: __________________

Today’s goals • Measure DC voltage, resistance, and continuity safely. • Relate voltage, current, resistance, power, and capacity.

Key vocabulary

Term	Working definition
voltage
current
resistance
power
capacity
DC
continuity
open circuit
short circuit

Meter safety Black lead in COM. Red lead in V/Ω. Resistance and continuity are measured only with the circuit unpowered. Do not use the current socket in this lesson.

1. Before measuring

☐ I checked the black lead is in COM.

☐ I checked the red lead is in V/Ω.

☐ I selected DC voltage, resistance, or continuity as instructed.

☐ I confirmed whether the circuit should be powered or unpowered.

2. Measurement stations

Station	Meter mode	Probe positions	Expected	Measured	Interpretation
A: cell/supply voltage	DC V
B: resistor	Ω
C: closed switch	Continuity
D: open switch	Continuity
E: buck input voltage	DC V

3. Calculation

A pump is labelled 12V, 5W. Estimate its running current using I = P ÷ V.

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A battery is labelled 40Ah. Explain why this does not mean it forces 40A through the pump.

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4. Error analysis

Mistake	What could happen?	Correct practice
Measure resistance on a powered circuit
Red lead left in current socket
Probe tips bridge two nearby terminals
Voltage measured with both probes on the same wire

Exit ticket

Write one safe and one unsafe multimeter practice.

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