How is an LED biased when emitting light?
The correct answer is D: Forward biased. How an LED is biased when emitting light is forward biased. LEDs only emit light when forward biased (positive voltage on anode, negative on cathode). For amateur radio operators, this is fundamental LED operation. Understanding this helps when using LEDs.
Exam Tip
LED emitting light = forward biased. Think 'L'ED = 'L'ight 'E'mits when 'D'iodes forward biased. LEDs only emit light when forward biased (positive anode, negative cathode). Not tunnel effect, not Zener voltage, not reverse biased - just forward biased.
Memory Aid
"LED emitting light = forward biased. Think 'L'ED = 'L'ight 'E'mits when 'D'iodes forward. LEDs only emit light when forward biased. Standard LED operation requirement."
Real-World Application
You connect an LED in a circuit. The LED only emits light when forward biased - positive voltage on the anode, negative on the cathode. Reverse biasing an LED doesn't produce light. Forward bias is required for LED operation.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. LEDs don't operate in the tunnel-effect region - that's for tunnel diodes, not LEDs. Tunnel effect isn't for LEDs.
Option B: Incorrect. LEDs don't operate at Zener voltage - that's for Zener diodes in reverse breakdown. Zener voltage isn't for LED operation.
Option C: Incorrect. LEDs don't emit light when reverse biased - they only emit when forward biased. Reverse bias doesn't produce light.
题目解析
The correct answer is D: Forward biased. How an LED is biased when emitting light is forward biased. LEDs only emit light when forward biased (positive voltage on anode, negative on cathode). For amateur radio operators, this is fundamental LED operation. Understanding this helps when using LEDs.
考试技巧
LED emitting light = forward biased. Think 'L'ED = 'L'ight 'E'mits when 'D'iodes forward biased. LEDs only emit light when forward biased (positive anode, negative cathode). Not tunnel effect, not Zener voltage, not reverse biased - just forward biased.
记忆口诀
LED emitting light = forward biased. Think 'L'ED = 'L'ight 'E'mits when 'D'iodes forward. LEDs only emit light when forward biased. Standard LED operation requirement.
实际应用示例
You connect an LED in a circuit. The LED only emits light when forward biased - positive voltage on the anode, negative on the cathode. Reverse biasing an LED doesn't produce light. Forward bias is required for LED operation.
错误选项分析
Option A: Incorrect. LEDs don't operate in the tunnel-effect region - that's for tunnel diodes, not LEDs. Tunnel effect isn't for LEDs. Option B: Incorrect. LEDs don't operate at Zener voltage - that's for Zener diodes in reverse breakdown. Zener voltage isn't for LED operation. Option C: Incorrect. LEDs don't emit light when reverse biased - they only emit when forward biased. Reverse bias doesn't produce light.
知识点
LED, Forward biased, Light emission, Diode operation
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.