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1) Glass rectifiers are usually made into units capable of D.C. output (maximum continuous rating) of _____________? a. 100 A at 100 V b. 200 A at 200 V c. 300 A at 300 V d. 400 A at 400 V e. 500 A at 500 V
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2) The cathdde voltage drop, in a mercury arc rectifier, is due to_____________? a. expenditure of energy in ionization b. surface resistance c. expenditure of energy in overcoming the electrostatic field d. expenditure of energy in liberating electrons from the mercury
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3) To produce cathode spot in a mercury arc rectifier______________? a. anode is heated b. tube is evacuated c. an auxiliary electrode is used d. low mercury vapour pressures are used
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4) The advantage of mercury arc rectifier is that________________? a. it is light in weight and occupies small floor space b. it has high efficiency c. it has high overload capacity d. it is comparatively noiseless e. all of the above
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5) The internal efficiency of a mercury arc rectifier depends on___________? a. voltage only b. current only c. voltage and current d. r.m.s. value of current e. none of the above
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6) In a mercury pool rectifier, the voltage drop across its electrodes___________? a. is directly proportional to load b. is inversely proportional to load c. varies exponentially with the load current d. is almost independent of load current
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7) If cathode and anode connections in a mercury arc rectifier are inter changed_____________? a. the rectifier will not operate b. internal losses will be reduced c. both ion and electron streams will move in the same direction d. the rectifier will operate at reduced efficiency
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8) The voltage drop at anode, in a mercury arc rectifier is due to_____________? a. self restoring property of mercury b. high ionization potential c. energy spent in overcoming the electrostatic field d. high temperature inside the rectifier
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9) The voltage drop between the anode and cathode, of a mercury arc rectifier comprises of the following_____________? a. anode drop and cathode drop b. anode drop and arc drop c. cathode drop and arc drop d. anode drop, cathode drop and arc drop
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10) The ionization potential of mercury is approximately_____________? a. 5.4 V b. 8.4 V c. 10.4 V d. 16.4 V
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