Question 42 QMED02 - Electrician-Refrigerating Engineer

The Correct Answer is B ### Explanation of Correct Option (B) Option B states that the semiconductor diode has **longer life**, **no warmup time**, and is **less delicate** than the vacuum tube diode. This statement accurately reflects the general advantages of solid-state semiconductor devices over vacuum tubes: 1. **Longer Life:** Semiconductor diodes (like silicon or germanium) are solid-state devices with no moving parts, filaments that burn out, or vacuum seals that degrade. Vacuum tubes rely on a heated filament (cathode) which has a finite operational life before it fails, making semiconductor diodes inherently longer-lived. 2. **No Warmup Time:** Vacuum tube diodes require the filament to heat up to thermionic emission temperatures before they can conduct electricity effectively, requiring a significant "warmup time" (often seconds to minutes). Semiconductor diodes operate instantly upon application of voltage, thus requiring **no warmup time**. 3. **Less Delicate:** While semiconductor chips themselves can be damaged by massive overvoltage, the packaged semiconductor diode is generally considered less delicate in terms of physical handling, vibration, and shock compared to the fragile glass envelope and internal structure of a vacuum tube. ### Explanation of Incorrect Options **A) The semiconductor diode has shorter life, no warmup time, and is less delicate than the vacuum tube diode.** * **Incorrect:** The semiconductor diode has a significantly **longer life** than the vacuum tube diode. **C) The semiconductor diode has longer life, longer warmup time, and is less delicate than the vacuum tube diode.** * **Incorrect:** The semiconductor diode has **no warmup time**, not a longer warmup time. **D) The semiconductor diode has longer life, no warmup time, and is more delicate than the vacuum tube diode.** * **Incorrect:** While semiconductors are sensitive to specific electrical phenomena (like static discharge), the overall packaged semiconductor diode is considered **less delicate** in terms of physical fragility, vibration resistance, and shock tolerance compared to the glass and wire construction of a vacuum tube.