Microampere current through a kilo-ohm resistor: for I = 200 µA flowing in R = 6.8 kΩ, compute the voltage drop across the resistor using V = I * R.

Difficulty: Easy

Correct Answer: 1.36 V

Explanation:


Introduction / Context:
Working with microampere currents and kilo-ohm resistors is common in sensor and instrumentation circuits. Converting prefixes correctly before applying V = I * R avoids common order-of-magnitude mistakes.


Given Data / Assumptions:

  • I = 200 µA = 200 × 10^-6 A = 0.0002 A.
  • R = 6.8 kΩ = 6.8 × 10^3 Ω = 6800 Ω.
  • Compute V = I * R.


Concept / Approach:

Convert to base SI units, multiply, and then, if needed, present the result in convenient volts. A quick exponent check helps confirm the decimal placement.


Step-by-Step Solution:

V = I * R = 0.0002 * 6800 = 1.36 V.Exponent check: (200 × 10^-6) * (6.8 × 10^3) = (200 * 6.8) × 10^-3 = 1360 × 10^-3 = 1.36 V.


Verification / Alternative check:

Power: P = V * I = 1.36 * 0.0002 = 0.000272 W = 0.272 mW, which is reasonable for small-signal applications.


Why Other Options Are Wrong:

13.6 V and 34.4 V are an order of magnitude too large; 340 V is two orders too large for these values.


Common Pitfalls:

Misreading µA as mA; forgetting to convert kΩ to Ω; slipping a decimal when multiplying.


Final Answer:

1.36 V

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