Vacuum Tubes

41. The equation that defines the dc plate resistance of a vacuum tube.

1. E_b/l_b
2. l_b² x E_b
3. l_b x E_b
4. l_b/E_b

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42. The filament voltage is a direct measure of

1. filament temperature
2. amplification
3. plate temperature
4. filament resistance

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43. The grid to palate capacitance is least in _________ valve

1. triode
2. tetrode
3. pentode
4. diode

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44. The indirectly heated cathode of the diode is coated with

1. thoriated tungsten
2. nickel
3. carbon
4. strontium or barium oxide

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45. The internal resistance after ionization of a gas-filled tube is

1. low
2. very high
3. high
4. zero

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46. The internal resistance of a gas-filled tube is _________ _ that of a vacuum tube.

1. the same as
2. less than
3. more than
4. dependent

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47. The ionization potential in a gas diode depends upon

1. plate current
2. size of the tube
3. cathode construction
4. type and pressure of gas

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48. The load resistance R in a triode amplifier should be nearly _________ for good amplification.

1. ½ r_p
2. 3 r_p
3. r_p
4. 2 r_p

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49. The negative resistance characteristics of the tetrode is due to

1. secondary emission
2. plate being positive with respect to cathode
3. control grid being negative with respect to cathode
4. screen grid being negative with respect to cathode

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50. The nose in a gas-filled tube is _________ that of a vacuum tube.

1. the same as
2. less than
3. more than
4. very much smaller than

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