Answer
The four sources are:
1) Voltage controlled Voltage source (V/V)
2) Current controlled Current source (A/A)
3) Current controlled Voltage source (A/V)
4) Voltage controlled current source (V/A)
Work Step by Step
Recall, there are both Current sources and Voltage sources. Of these sources, each source can be controlled by Voltage or Current, giving a total of four options. Also, recall that the unit for Voltage is Volts, and the unit for current is Amps. Thus, we obtain the following possibilities with their units:
1) Voltage controlled Voltage source (V/V)
2) Current controlled Current source (A/A)
3) Current controlled Voltage source (A/V)
4) Voltage controlled current source (V/A)
