19 3-36.   With only capacitance and inductance of the line given, the time (T) required for a voltage change to travel down a transmission line can be found by what formula? The characteristic impedance for an infinite transmission line can be figured using which of the following ratios? 1. 3. 2. 4. 3-37.   The characteristic impedance for an infinite transmission line can be figured using which of the following ratios? 1.   Input current to velocity 2.   Input voltage to input current 3.   Input voltage to line resistance 4.   Input current to line resistance 3-38.   The characteristic impedance of a transmission line can be figured by using which of the following formulas? 1. 3. 2. 4. Figure 3-C.—Equivalent transmission line. IN ANSWERING QUESTIONS 3-39 AND 3-40, REFER TO FIGURE 3-C. ASSUME THAT THE LINE IS 1,200 FEET LONG. A 150-FOOT SECTION IS MEASURED TO DETERMINE L AND C. THE 150-FOOT SECTION HAS AN INDUCTANCE OF 0.36 MILLIHENRIES AND A CAPACITANCE OF 1,000 PICOFARADS. 3-39.   What is the characteristic impedance of the line? 1.   400 ohms 2.   600 ohms 3.   800 ohms 4.   900 ohms 3-40.   What is the velocity of the wave on the 150-foot section? 1.   210,000,000 fps 2.   225,000,000 fps 3.   250,000,000 fps 4.   275,000,000 fps 3-41.   If a transmission line is open-ended, which of the following conditions describes its terminating impedance? 1.   Finite 2.   Infinitely large 3.   Equal to load impedance 4.   Equal to source impedance