Deep Dive: E7D09
The correct answer is C: Capacity in amp-hours divided by average current. How is battery operating time calculated is capacity in amp-hours divided by average current. Operating time = capacity / current. For amateur radio operators, this is important for battery calculations. Understanding this helps when planning battery usage.
Why Other Answers Are Wrong
Option A: Incorrect. Average current divided by capacity isn't correct - operating time = capacity / current. Current/capacity is wrong. Option B: Incorrect. Average current divided by internal resistance isn't correct - operating time = capacity / current. Current/resistance is wrong. Option D: Incorrect. Internal resistance divided by average current isn't correct - operating time = capacity / current. Resistance/current is wrong.
Exam Tip
Battery operating time = capacity in amp-hours / average current. Think 'B'attery 'T'ime = 'C'apacity / 'C'urrent. Operating time = capacity / current. Not current/capacity, not current/resistance, not resistance/current - just capacity / current.
Memory Aid
Battery operating time = capacity in amp-hours / average current. Think 'B'attery 'T'ime = 'C'apacity / 'C'urrent. Operating time = capacity / current. Important for battery calculations.
Real-World Example
Battery operating time: It's calculated as capacity in amp-hours divided by average current. For example, a 10 Ah battery with 2 A average current gives 10/2 = 5 hours. This is the calculation - capacity / current.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E7D
Reference: 2024-2028 Question Pool · E7 - Practical Circuits
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E7D topic.