Voltage with SI prefixes: Seven thousand volts should be written using a single standard prefix as which of the following?
Electronics
Quantities and Units
Difficulty: Easy
Choose an option
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A7 kV
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B7 MV
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C7 mV
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Deither 7 kV or 7 mV
Answer
Correct Answer: 7 kV
Explanation
Introduction / Context:Expressing values with the correct SI prefix keeps specifications concise and unambiguous. Here we convert a raw number of volts into a properly prefixed voltage unit.
Given Data / Assumptions:
- Given voltage: 7000 V.
- Prefixes: kilo (k) = 10^3, mega (M) = 10^6, milli (m) = 10^-3.
- Goal: choose the correct single-prefix expression.
Concept / Approach:For thousands, use kilo. Divide by 10^3 to convert volts to kilovolts. Mega and milli would misrepresent the magnitude by many orders of magnitude.
Step-by-Step Solution:
Compute: 7000 V / 1000 = 7 kV.Check scale: 7 MV = 7 × 10^6 V (far larger); 7 mV = 7 × 10^-3 V (far smaller).Select the exact matching option: '7 kV'.Verification / Alternative check:Reverse operation: 7 kV × 1000 = 7000 V. This confirms the choice precisely.
Why Other Options Are Wrong:
- 7 MV: Equals 7,000,000 V; not equivalent.
- 7 mV: Equals 0.007 V; not equivalent.
- either 7 kV or 7 mV: Includes an obviously incorrect alternative.
Common Pitfalls:
- Confusing uppercase M (mega) with lowercase m (milli).
- Overlooking that kV is the standard way to express thousands of volts.
Final Answer:7 kV