SI Units and Prefixes
Match ohm, watt, hertz, ampere and volt to resistance, power, frequency, current and potential difference, then apply mega, kilo and milli.
Prepare from maintenance duty to traceable decision
Start with responsibility and risk, classify the equipment, inspect before testing, choose relevant measurements, interpret all evidence and complete an honest record.
Core concepts
Concept 1
Match ohm, watt, hertz, ampere and volt to resistance, power, frequency, current and potential difference, then apply mega, kilo and milli.
Exam cue: Write the quantity, base unit and prefix multiplier before converting; carry the unit through every step.
Concept 2
Mega is one million, kilo is one thousand and milli is one thousandth of the base unit.
Exam cue: Separate the evidence needed for the written decision from the live competence required to obtain it safely.
Concept 3
A result without its unit and scale can be misread by factors of one thousand or one million.
Concept 4
Use the instrument range and displayed prefix actually stated; do not invent resolution or accuracy.
Targeted study blocks
Purpose
Identify the safety decision
Match ohm, watt, hertz, ampere and volt to resistance, power, frequency, current and potential difference, then apply mega, kilo and milli.
Method
Use an evidence-led sequence
Write the quantity, base unit and prefix multiplier before converting; carry the unit through every step.
Boundary
Preserve practical and legal limits
Use the instrument range and displayed prefix actually stated; do not invent resolution or accuracy. Do not interchange MΩ, kΩ and Ω or treat mA as A.
Risk pitfalls and guardrails
Do not interchange MΩ, kΩ and Ω or treat mA as A.
Guardrail: Inspect first, use only relevant tests and keep the written decision within the practical and legal boundary.
Do not treat a fixed interval, one reading or a test label as the complete maintenance decision.
Guardrail: Inspect first, use only relevant tests and keep the written decision within the practical and legal boundary.
Memory anchors
SI Units and Prefixes: purpose
Match ohm, watt, hertz, ampere and volt to resistance, power, frequency, current and potential difference, then apply mega, kilo and milli.
SI Units and Prefixes: method
Write the quantity, base unit and prefix multiplier before converting; carry the unit through every step.
SI Units and Prefixes: key fact 1
Mega is one million, kilo is one thousand and milli is one thousandth of the base unit.
SI Units and Prefixes: key fact 2
A result without its unit and scale can be misread by factors of one thousand or one million.
SI Units and Prefixes: boundary
Use the instrument range and displayed prefix actually stated; do not invent resolution or accuracy.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
Which SI unit is used for electrical resistance?
Which SI unit is used for electric current?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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