What is the approximate forward threshold voltage of a germanium diode?
The correct answer is B: 0.3 volts. The approximate forward threshold voltage of a germanium diode is 0.3 volts. Germanium diodes have lower forward voltage than silicon diodes. For amateur radio operators, this is important for circuit design. Understanding this helps when selecting diodes.
Exam Tip
Germanium diode forward voltage = 0.3 volts. Think 'G'ermanium = 'G'enerally '0'.3V. Germanium diodes have lower forward voltage than silicon (0.7V). Not 0.1V, not 0.7V (silicon), not 1.0V - just 0.3V.
Memory Aid
"Germanium diode forward voltage = 0.3 volts. Think 'G'ermanium = 'G'enerally '0'.3V. Germanium diodes have lower forward voltage than silicon. Useful for low-voltage applications."
Real-World Application
You use a germanium diode in a detector circuit. The diode starts conducting at about 0.3 volts forward voltage. This is lower than silicon diodes (0.7V), making germanium useful for low-voltage applications. Germanium's lower forward voltage is a key characteristic.
Key Concepts
Why Other Options Are Wrong
Option A (0.1 volt): Incorrect. 0.1 volt is too low - germanium diodes have about 0.3V forward voltage, not 0.1V. 0.1V is too low.
Option C (0.7 volts): Incorrect. 0.7 volts is for silicon diodes, not germanium. Germanium has lower forward voltage than silicon.
Option D (1.0 volts): Incorrect. 1.0 volt is too high - that's more like LED forward voltage. Germanium is 0.3V.
题目解析
The correct answer is B: 0.3 volts. The approximate forward threshold voltage of a germanium diode is 0.3 volts. Germanium diodes have lower forward voltage than silicon diodes. For amateur radio operators, this is important for circuit design. Understanding this helps when selecting diodes.
考试技巧
Germanium diode forward voltage = 0.3 volts. Think 'G'ermanium = 'G'enerally '0'.3V. Germanium diodes have lower forward voltage than silicon (0.7V). Not 0.1V, not 0.7V (silicon), not 1.0V - just 0.3V.
记忆口诀
Germanium diode forward voltage = 0.3 volts. Think 'G'ermanium = 'G'enerally '0'.3V. Germanium diodes have lower forward voltage than silicon. Useful for low-voltage applications.
实际应用示例
You use a germanium diode in a detector circuit. The diode starts conducting at about 0.3 volts forward voltage. This is lower than silicon diodes (0.7V), making germanium useful for low-voltage applications. Germanium's lower forward voltage is a key characteristic.
错误选项分析
Option A (0.1 volt): Incorrect. 0.1 volt is too low - germanium diodes have about 0.3V forward voltage, not 0.1V. 0.1V is too low. Option C (0.7 volts): Incorrect. 0.7 volts is for silicon diodes, not germanium. Germanium has lower forward voltage than silicon. Option D (1.0 volts): Incorrect. 1.0 volt is too high - that's more like LED forward voltage. Germanium is 0.3V.
知识点
Germanium diode, Forward threshold voltage, 0.3 volts, Diode characteristics
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.