Comparing Currents by Unit Conversion

Steps:

• Convert 2 μA to amperes: 2 × 10^{-6} A.
• Convert 1 mA to amperes: 1 × 10^{-3} A.
• Compute ratio: \frac{10^{-3}}{2 \times 10^{-6}} = \frac{1}{2} \times 10^{3} = 500.
• The second current is 500 times the first.

Why A is correct:

• The ratio equals 500 when both currents are in amperes, per the definition of electric current as charge flow rate.

Why the others are wrong:

• B ignores the factor of 2 in the numerator, yielding 1000 instead of 500.
• C multiplies by an extra 10, mistaking μA to mA conversion.
• D multiplies by an extra 100, confusing prefixes like μA to A directly.

Final answer: A