 Solution

ID: past-exam-of-the-physics-a-course-of-the-university-of-cambridge/2012/paper-1/section-d/d13/a/solution

Zero capacitance removes the capacitor branches. No current enters the non-inverting input, so no current flows through

R_{1}

R_{2}

and

V_{+} = V_{in}

. The inverting divider gives

V_{-} = V_{out} R_{3} / (R_{3} + R_{4})

. Equating the two input voltages in the linear solution gives

\frac{V _{out}}{V _{in}} = 1 + \frac{R _{4}}{R _{3}} = K .

 New to topics? Read the docs here!