Electronics I and Lab
AC Models

1. The impedance of a capacitor is inversely proportional to the frequency and the capacitor effectively blocks dc voltage.
a. True
b. False

2. A coupling capacitor couples an ac signal into an amplifier without disturbing its operating point.
a. True
b. False

3. The voltage gain of an amplifier is defined as the ac output voltage divided by the ac input voltage.
a. True
b. False

4. The ac resistance of the emitter diode equals the ac base-emitter voltage divided by the ac emitter current.
a. True
b. False

5. The common-collector amplifier has:
a. its collector at ac ground
b. its collector at dc ground
c. its emitter at ac ground
d. its emitter at dc ground

6. The ac collector current divided by the ac base current is referred to as:
a. dc current gain.
b. ac current gain.
c. alpha.
d. delta.

7. Refer to the figure 1 below, what is the lowest frequency at which good coupling exists?

Figure 1

8. Given the parameters in figure 2 below calculate:
a. ac resistance of the emitter diode
b. if the emitter resistance is doubled, what is the ac resistance of the emitter diode?
c. explain in your own words the relationship of the emitter diode and the ac resistance of the ac emitter diode?

Figure 2

9. Using the values listed on the circuit shown in figure 3 below:
a. what effect do the capacitors have on the dc biasing?
b. What type of amplifier is in figure 3 below?

10. Which statement is true with regard to the circuit shown in figure 3 below?
a. the ac signal out of the transistor is amplified and inverted
b. the ac signal out of the transistor is amplified and in-phase with the input
c. the ac signal out of the transistor is not amplified
d. the ac signal out of the transistor is attenuated