How is the cathode lead of a semiconductor diode often marked on the package?
The correct answer is B: With a stripe. The cathode lead of a semiconductor diode is typically marked on the package with a stripe, band, or line. This visual marking is a standard industry practice that makes it easy to identify diode polarity without needing to test the component. The stripe indicates the cathode (negative) terminal, while the unmarked end is the anode (positive) terminal. This marking is crucial for proper circuit installation, as diodes only work when connected with correct polarity. For amateur radio operators, being able to quickly identify diode polarity is essential when building or repairing equipment, installing protection diodes, or working with rectifier circuits. The stripe marking is consistent across most diode types, making it a reliable identification method.
Exam Tip
Diode cathode is marked with a stripe. Think 'S'tripe = 'S'ide with cathode. This is the standard industry marking - simple and universal. The stripe always indicates the cathode (negative) end.
Memory Aid
"Cathode = Stripe. Think 'C'athode has a 'S'tripe. The striped end is the cathode (negative) terminal."
Real-World Application
When installing a protection diode in your power supply circuit, you look for the stripe on the diode body. The striped end (cathode) connects to the positive supply line, and the unmarked end (anode) connects to ground. This reverse-biases the diode under normal conditions, but if voltage is accidentally reversed, the diode conducts and protects your circuit. The stripe makes it easy to orient the diode correctly without testing.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. While some specialized diodes might have text labels, the standard marking is a simple stripe, not the word 'cathode.' Text markings are not common on small signal diodes.
Option C: Incorrect. The letter 'C' is not the standard marking for cathode. The stripe is the universal marking method used across the industry.
Option D: Incorrect. While 'K' is sometimes used in schematics to denote cathode, the physical package marking is a stripe, not the letter K.
题目解析
The correct answer is B: With a stripe. The cathode lead of a semiconductor diode is typically marked on the package with a stripe, band, or line. This visual marking is a standard industry practice that makes it easy to identify diode polarity without needing to test the component. The stripe indicates the cathode (negative) terminal, while the unmarked end is the anode (positive) terminal. This marking is crucial for proper circuit installation, as diodes only work when connected with correct polarity. For amateur radio operators, being able to quickly identify diode polarity is essential when building or repairing equipment, installing protection diodes, or working with rectifier circuits. The stripe marking is consistent across most diode types, making it a reliable identification method.
考试技巧
Diode cathode is marked with a stripe. Think 'S'tripe = 'S'ide with cathode. This is the standard industry marking - simple and universal. The stripe always indicates the cathode (negative) end.
记忆口诀
Cathode = Stripe. Think 'C'athode has a 'S'tripe. The striped end is the cathode (negative) terminal.
实际应用示例
When installing a protection diode in your power supply circuit, you look for the stripe on the diode body. The striped end (cathode) connects to the positive supply line, and the unmarked end (anode) connects to ground. This reverse-biases the diode under normal conditions, but if voltage is accidentally reversed, the diode conducts and protects your circuit. The stripe makes it easy to orient the diode correctly without testing.
错误选项分析
Option A: Incorrect. While some specialized diodes might have text labels, the standard marking is a simple stripe, not the word 'cathode.' Text markings are not common on small signal diodes. Option C: Incorrect. The letter 'C' is not the standard marking for cathode. The stripe is the universal marking method used across the industry. Option D: Incorrect. While 'K' is sometimes used in schematics to denote cathode, the physical package marking is a stripe, not the letter K.
知识点
Diode marking, Cathode identification, Diode polarity, Component identification
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.