Question

What is the effect of the capacitor at the position 1?

Connection of in puit oxpling swith Input - 2. To inpuct anpl:ier

Answer 1

When the switch is at position 1, the input to connected to the amplifier. The capacitor used in between the input and the amplifier is a coupling capacitor that blocks the DC components in the signal and only passes the high-frequency components.

To understand this, first, you need to know how the capacitor offers impedance to various frequencies.

The impedance offered by a capacitor is given by Z = 1/jwC, where w is input frequency in rad/sec C is the capacitance of the capacitor. From this impedance relation one can establish the fact that as the frequency increases, the impedance of the capacitor reduces and likewise if the frequency reduces, the impedance increases. The impedance of capacitor for DC component is given by 1/0 = infinity. which means that the capacitor is equivalent to open circuit for DC components. And for high-frequency signals, the capacitor impedance is very less and hence the capacitor passes the high-frequency components with minimal impedance.