9 ________________________________________ IN ANSWERING QUESTIONS 1-64 THROUGH 1-66, MATCH THE ELECTRICAL LETTER SYMBOL FOR RECTIFIER DIODES IN COLUMN B TO THE DEFINITION IN COLUMN A. A.  DEFINITIONS B.  SYMBOLS 1-64. The maximum reverse dc voltage that will not cause breakdown 1. V_R 1-65. The peak current specified for a given number of cycles or portion of a cycle 2. I_SURGE 1-66. The average reverse current at a specified temperature, usually 60 hertz 3. 4. I_F(AV) I_R(AV) ________________________________________ 1-67.   A matching pair of diodes is indicated by which of the following numbers? 1. 2N325 2.    1N325C 3.    2N325M 4.    1N325M 1-68.   The number 3N345 identifies which of the following semiconductors, if any? 1.    Diode 2.    Transistor 3.    Tetrode transistor 4.    None of the above 1-69.   What type of diode has green, blue, and orange bands? 1. 1N463 2. 1N572 3. 1N663 4. 1N563 1-70.   One of the prime dangers to the semiconductor diode is heat. Excessive current generated by heat  which eventually destroys a diode is called 1.    junction overload 2.    thermal runaway 3.    thermoplastic action 4.    thermionic emission 1-71.   When replacing a diode in a circuit, which of the following safety precautions should you observe in removing the diode from the circuit? 1.    Do not pry the diode from the circuit 2.    Do not use excessive heat to remove the diode 3.    Do not remove the diode from the circuit while voltage is applied 4.    All of the above 1-72.   As you make a front-to-back ratio check of a diode with an ohmmeter, your first measurement (forward) is a low resistance reading, and your second measurement (reverse) is also a low reading. What should be your evaluation of the diode? 1.    It is open 2.    It is shorted 3.    It is good 4.    It is leaky 1-73.   What are normally the front-to-back ratio of (a) a power rectifier and (b) a signal diode? 1.    (a)   10:1 (b)   50:1 2.    (a)   10:1 (b) 300:1 3.    (a) 300:1 (b)   10:1 4.    (a) 300:1 (b)   50:1