Open Loop Voltage Gain (Av)
The open loop voltage gain (Av) of a feedback network refers to the amplification factor of the system when no feedback is applied. In this case, the open loop voltage gain is given as -100.

Input Voltage to the System (Vin')
The input voltage to the system, denoted as Vin', is given as 1mV. This represents the voltage signal that is applied to the input of the amplifier.

Closed Loop Voltage Amplification (Acl)
To determine the closed loop voltage amplifier, we need to consider the effect of feedback on the system. In a feedback network, a portion of the output voltage is fed back to the input, resulting in a modified gain. The closed loop voltage amplification (Acl) can be calculated using the formula:

Acl = Av / (1 + Av * β)

Where Av is the open loop voltage gain and β is the feedback factor.

Calculation of Closed Loop Voltage Amplification (Acl)
In this case, the open loop voltage gain (Av) is -100. To determine the closed loop voltage amplification (Acl), we need to know the feedback factor (β). Unfortunately, the feedback factor is not provided in the given information. Hence, it is not possible to calculate the closed loop voltage amplifier without the feedback factor.

Importance of Feedback Factor (β)
The feedback factor (β) represents the fraction of the output voltage that is fed back to the input. It plays a crucial role in determining the effect of feedback on the system. Depending on the value of β, the closed loop voltage amplification (Acl) can be significantly different from the open loop voltage gain (Av). Therefore, without knowing the feedback factor, it is not possible to accurately determine the closed loop voltage amplifier.

Conclusion
In this scenario, the closed loop voltage amplifier cannot be determined without the feedback factor. The feedback factor is necessary to calculate the closed loop voltage amplification using the provided formula. It is important to have complete information about the feedback network in order to accurately analyze and determine the closed loop voltage amplifier.