Vacuum Tubes

31. Oxide coated emitters have electron emission of _________ per watt of heated power.

1. 5-10 A
2. 50-100 A
3. 50-150 mA
4. 150-1000 mA

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32. Plate saturation results when

1. filament voltage is too high
2. space-charge region is depleted
3. plate temperature is too low
4. space-charge region is saturated

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33. Saturation in a tube is a condition where an increase in plate voltage will produce

1. a rise in electron emission
2. a decrease in electron emission
3. no appreciable change in plate current
4. an appreciable change in plate current

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34. Secondary emission effects are undesirable in

1. vacuum tubes
2. gas-filled tubes
3. lCs
4. transistors

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35. The _________ voltage should be reduced to zero to stop conduction in a thyratron.

1. grid
2. filament
3. plate
4. heater

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36. The actual voltage gain of a triode amplifier is less than μ due to

1. grid being negative with respect to cathode
2. voltage drop in ac resistance of the tube
3. plate being positive with respect to cathode
4. voltage drop in dc resistance of the tube

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37. The anode-cathode potential of a gas-filled tube at which gas de-ionizes and stops conduction is called _________ potential.

1. extinction
2. ionizing
3. striking
4. reverse

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38. The cathode heating time of thermionic glass diode is _________ that of a vacuum diode.

1. the same as
2. much less than
3. much more than
4. not related to

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39. The electrons emitted by a thermionic emitter are called

1. free electrons
2. thermionic electrons
3. loose electrons
4. bound electrons

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40. The equation that defines the ac plate resistance of a vacuum tube?

1. Eb/ Ec
2. lb/ Ec
3. tiEb/tiEb
4. Ec/ lb

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