Deep Dive: T5D05
The correct answer is C: 8 ohms. For a circuit with applied voltage of 12 volts and current flow of 1.5 amperes, the resistance is 8 ohms. Using Ohm's Law: R = E / I = 12 / 1.5 = 8 ohms. This calculation demonstrates how to find resistance when you know voltage and current. The formula R = E / I is straightforward: divide 12 volts by 1.5 amperes to get 8 ohms. This type of calculation is essential for understanding circuit behavior, selecting proper components, and troubleshooting. The result shows that an 8-ohm resistor will allow 1.5 amperes to flow when 12 volts is applied.
Why Other Answers Are Wrong
Option A: Incorrect. 18 ohms would be multiplying voltage and current (12 × 1.5), which gives power (18 watts), not resistance. Option B: Incorrect. 0.125 ohms would be dividing current by voltage (1.5 / 12), which is the inverse of the correct formula. Option D: Incorrect. 13.5 ohms would be adding voltage and current (12 + 1.5), which is mathematically incorrect.
Exam Tip
Resistance = Voltage / Current. Remember: R = 12V / 1.5A = 8 ohms. Divide voltage by current, not the other way around.
Memory Aid
**R** = **1**2V / **1**.**5**A = **8**Ω (think '12/1.5 = 8')
Real-World Example
You're testing a 12-volt power supply. You connect a load and measure 1.5 amperes of current. Using R = E / I, you calculate the load resistance: R = 12 / 1.5 = 8 ohms. This confirms the load value and helps you verify proper operation.
Source & Coverage
Question Pool: 2022-2026 Question Pool
Subelement: T5D
Reference: 2022-2026 Question Pool · T5 - Electrical principles
Key Concepts
Verified Content
Question from the official FCC Technician Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the T5D topic.