Current unit conversion — express in milliampere: 7450 × 10^–5 amperes equals 74.5 what unit?

Introduction / Context:
Converting between base SI units and engineering prefixes is routine in electronics. Expressing a current in milliamperes is often more intuitive for circuit analysis and component ratings, such as the forward current of diodes or the quiescent current of ICs.

Given Data / Assumptions:

• Quantity: 7450 × 10^–5 A.
• We want an equivalent form stated as 74.5 (numeric) followed by the correct unit symbol.
• Useful relations: 1 mA = 10^–3 A; 1 µA = 10^–6 A; 1 nA = 10^–9 A.

Concept / Approach:
Simplify the scientific notation to a decimal in amperes, then change units to a convenient engineering prefix so that the numeric part matches 74.5. Recognize that milliamperes are thousandths of an ampere, so multiplying amperes by 1000 converts to milliamperes.

Step-by-Step Solution:

Verification / Alternative check:
Convert directly: 10^–5 A = 0.01 mA. Then 7450 × 0.01 mA = 74.5 mA. Both paths agree, confirming the result.

Why Other Options Are Wrong:
A (amperes) would be 0.0745 A, not 74.5 A. µA would be 74,500 µA, not 74.5 µA. nA would be 74,500,000 nA. kA is orders of magnitude too large.

Common Pitfalls:
Losing track of decimal placement when switching between prefixes, and confusing 10^–5 with 10^–3 (milli) or 10^–6 (micro). Always rewrite to base units first if unsure.

Final Answer:
mA