17 3-21. For a given voltage, what determines the amount of current that will flow in a transmission line? 1. Conductance2. Spacing of the wires 3. Diameter of the wires 4. Characteristic impedance 3-22. When the impedance of a transmission line is measured, which of the following values frequently is NOT considered? 1. Inductance2. Resistance3. Conductance4. Capacitance3-23. The characteristic impedance of a long transmission line may be determined by using which of the following methods? 1. Trial and error 2. Calculating the impedance of the entire line 3. Calculating the impedances at each end of the line 4. Adding the impedances of successive short sections 3-24. When should lumped values for transmission-line constants be used to calculate characteristic impedance? 1. When the line is short compared to one wavelength2. When the line is long compared to one wavelength3. When the line is infinitely long 3-25. In actual practice, the characteristic impedance of a transmission line is usually within which of the following resistance ranges? 1. 0 to 0.9 ohm 2. 1 to 49 ohms 3. 50 to 600 ohms 4. 601 to 1,000 ohms 3-26. The input impedance of a transmission line is affected by which of the following properties? 1. Radiation loss 2. Series inductance3. Parallel capacitance4. Each of the above 3-27. When a dc voltage is applied to a transmission line and the load absorbs all the energy, what is the resulting relationship between current and voltage? 1. They are in phase with each other 2. They are equal to Z_{0} of the line 3. They are out of phase with each other 4. They are evenly distributed along the line 3-28. The initial waves that travel from the source to the load of a transmission lineare referred to as what type of waves? 1. Incident 2. Refracted 3. Reflected 4. Diffracted 3-29. Waves that travel from the output end to the input end of a transmission line are referred to as what type of waves? 1. Incident 2. Refracted 3. Reflected 4. Diffracted