Vacuum Tubes

91. Which emitter is used in high voltage (>10 kV) applications?

1. Tungsten
2. Oxide coated
3. Thoriated-tungsten
4. Constantan

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92. Which generates the least noise in operation?

1. Triode valve
2. Tetrode valve
3. Pentode valve
4. Octode valve

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93. Which is the best tube for high frequency amplification?

1. Triode valve
2. Tetrode valve
3. Pentode valve
4. Diode valve

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94. Which of the following defines the amplification factor of a vacuum tube?

1. ΔE_b/tiE_c
2. Δl_b/ E_b
3. ΔE_c/ E_b
4. ΔE_b/ lc

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95. Which of the following is a desirable characteristic of an emitter?

1. Large work function
2. Small work function
3. Very large work function
4. Very small work function

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96. Which of the following would have the most effect on decreasing the life of a vacuum tube?

1. Too much of a grid excitation
2. An excessive filament voltage
3. A grid current that is too low
4. A plate resistance value that is too high

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97. Which provides the best frequency response?

1. Transformer coupling
2. RC coupling
3. Direct coupling
4. lmpedance coupling

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98. Which thermionic emitter has the highest opening temperature?

1. Oxide coated
2. Tungsten
3. Thoriated-tungsten
4. Eureka

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99. Which tube generates the greatest noise?

1. Triode
2. Tetrode
3. Pentode
4. Diode

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100. Which valve has the lowest amplification factor?

1. Triode
2. Pentode
3. Tetrode
4. Diode

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