I'm uncertain about a few things regarding these circuit problems.
1) Determine Vout/Vin for the circuit ( see photo 1) and explain how it works when
a) The switch is connected to the ground
 Here I would think that Vout/Vin=R/R=1 and it would work as a magnifier where the same current goes through both resistors.
b) The switch is connected to Vin
I'm really not sure here, would it work like a noninverting amplifier with gain = 1. Would the resistor between the inputs have no affect?
2) Determine Vout/Vin for the circuit (see photo 2). Assume that it's a perfect operation amplifier (that is v+=v)
I think the 10kΩ would have virtually no effect here so it would simply be:
Vin=Va, Va=Vout*(20kΩ/(20kΩ+20kΩ+5kΩ))
so Vout/Vin=45kΩ/20kΩ=4.5
3) For the circuit (see photo 3)
a) Find the Vout/Vin
I got Vout/Vin = (R2 + 1/jωC)/(R2 + 1/jωC + R1)
But that ground troubles me, would it change anything?
b) Find the length of Vout/Vin, and what it would be if ω→0, ω→∞
Given that a) is correct I got Vout/Vin = sqrt(R2^2+1/ω^2C^2)/sqrt(R1^2+R2^2+1/ω^2C^2)
if ω→0 then Vout/Vin→1
if ω→∞ then Vout/Vin→R2/sqrt(R1^2+R2^2)
1) Determine Vout/Vin for the circuit ( see photo 1) and explain how it works when
a) The switch is connected to the ground
 Here I would think that Vout/Vin=R/R=1 and it would work as a magnifier where the same current goes through both resistors.
b) The switch is connected to Vin
I'm really not sure here, would it work like a noninverting amplifier with gain = 1. Would the resistor between the inputs have no affect?
2) Determine Vout/Vin for the circuit (see photo 2). Assume that it's a perfect operation amplifier (that is v+=v)
I think the 10kΩ would have virtually no effect here so it would simply be:
Vin=Va, Va=Vout*(20kΩ/(20kΩ+20kΩ+5kΩ))
so Vout/Vin=45kΩ/20kΩ=4.5
3) For the circuit (see photo 3)
a) Find the Vout/Vin
I got Vout/Vin = (R2 + 1/jωC)/(R2 + 1/jωC + R1)
But that ground troubles me, would it change anything?
b) Find the length of Vout/Vin, and what it would be if ω→0, ω→∞
Given that a) is correct I got Vout/Vin = sqrt(R2^2+1/ω^2C^2)/sqrt(R1^2+R2^2+1/ω^2C^2)
if ω→0 then Vout/Vin→1
if ω→∞ then Vout/Vin→R2/sqrt(R1^2+R2^2)
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