Updated: Dec 9, 2025 | Source: 2023-2027 Question Pool | Topic: G6A
G6A03G6A

What is the approximate forward threshold voltage of a germanium diode?

Deep Dive: G6A03

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.

Why Other Answers 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.

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 Example

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.

Source & Coverage

Question Pool: 2023-2027 Question Pool

Subelement: G6A

Reference: 2023-2027 Question Pool · G6 - Circuit Components

Key Concepts

Germanium diode Forward threshold voltage 0.3 volts Diode characteristics

Verified Content

Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G6A topic.