Question: Copper oxide rectifier is usually designed not to operate above___________?

• 1. 10°C
• 2. 20°C
• 3. 30°C
• 4. 45°C

Question: Ageing of a selenium rectifier may change the output voltage by__________?

• 1. 5 to 10 per cent
• 2. 15 to 20 per cent
• 3. 25 to 30 per cent
• 4. none of the above

Question: The efficiency of the copper oxide rectifier seldom exceeds____________?

• 1. 90 to 95%
• 2. 85 to 90%
• 3. 80 to 85%
• 4. 65 to 75%

Question: Selenium rectifier can be operated at temperatures as high as____________?

• 1. 25°C
• 2. 40°C
• 3. 60°C
• 4. 75°C

Question: The applications of selenium rectifiers are usually limited to potential of_____________?

• 1. 10 V
• 2. 30 V
• 3. 60 V
• 4. 100 V

Question: In selenium rectifiers efficiencies ranging from _______ to _______ percent are attainable?

• 1. 25, 35
• 2. 40, 50
• 3. 60, 70
• 4. 75, 85

Question: A commutating rectifier consists of commutator driven by___________?

• 1. an induction motor
• 2. a synchronous motor
• 3. a DC series motor
• 4. a DC shunt motor

Question: In a mercury arc rectifier, the anode is usually made of_____________?

• 1. copper
• 2. aluminium
• 3. silver
• 4. graphite

Question: Which of the following rectifiers have been used extensively in supplying direct current for electroplating ?

• 1. Copper oxide rectifiers
• 2. Selenium rectifiers
• 3. Mercury arc rectifiers
• 4. Mechanical rectifiers

Question: Which of the following is the loss within the mercury arc rectifier chamber ?

• 1. Voltage drop in arc
• 2. Voltage drop at the anode
• 3. Voltage drop at the cathode
• 4. All of the above