Deep Dive: T5D12
The correct answer is D: 20 volts. The voltage across a 10-ohm resistor if a current of 2 amperes flows through it is 20 volts. Using Ohm's Law: E = I × R = 2 × 10 = 20 volts. This is a direct application of Ohm's Law to find voltage. When 2 amperes flows through a 10-ohm resistor, the voltage across it is 20 volts. This calculation is fundamental for understanding circuit behavior and verifying component operation. The formula E = I × R shows that voltage is directly proportional to both current and resistance, which is essential for circuit design and troubleshooting.
Why Other Answers Are Wrong
Option A: Incorrect. 8 volts would be subtracting current from resistance (10 - 2), which is mathematically invalid. Voltage must be calculated as current times resistance. Option B: Incorrect. 0.2 volts would be dividing current by resistance (2 / 10), which is the inverse of the correct formula. Option C: Incorrect. 12 volts would be adding current and resistance (2 + 10), which is mathematically invalid.
Exam Tip
Voltage = Current × Resistance. Remember: E = 2A × 10Ω = 20V. Multiply current by resistance to find voltage.
Memory Aid
**E** = **2**A × **1**0Ω = **2**0V (think '2×10 = 20')
Real-World Example
You're testing a circuit. You measure 2 amperes flowing through a 10-ohm resistor. Using E = I × R, you calculate the voltage: E = 2 × 10 = 20 volts. This helps you verify the circuit operation and understand power dissipation (40 watts).
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.