Capacitor Uses

Part 1


In your own words, explain the use of a capacitor as an isolating component or as a filter for AC signals (HINT: Audio Amplifiers).
Give examples of other inductor applications.


Capacitor has a device which blocks dc and allows ac to flow through it. As we know that the capacitive reactance is given as:

XC =1/(2π*f*C)

For a dc component, f=0, XC= infinity, so the capacitor will behave as open circuit with infinite resistance and for an ac component, we have finite resistance in case of AC circuit.

So capacitor is used as a filter in AC circuits to block all the dc circuits.

Application of inductors:

  1. As receiver in FM radios.
  2. As filters and sensors.
  3. In motors and transformer coils.

Part 2


In your own words, discuss two applications of RL Circuits.


RL circuits are used in:

  1. DC power supplies

RL circuits normally comprised of a resistor and inductor in series to each other, are used as dc power supplies to RF amplifiers, where inductor passes DC bias current and block RF getting back into power supply.

  1. Coil in transformers

The RL circuit is used in the coil of transformers which can either be step up or step down transformers.

Part 3


Explain the basic differences between Direct and Alternating current, and give two examples of each that you use every day.


Differences between AC and DC current:

  1. AC current has a varying non-zero frequency whereas DC does not have the frequency component.
  2. AC current can reverse its direction while flowing in the circuit but the DC current flows in one direction only
  3. AC current has impedance, whereas DC current has resistance.
  4. AC current is sinusoidal in nature, DC is pure and pulsating.


DC current

  1. DC current is used in batteries for mobiles, cars.
  2. DC current is used in diodes, rectifiers of the circuits of various household components.

AC current

  1. We receive AC supply in our homes, hence used in all electric appliances.
  2. The most common applications for alternating (AC) current are in producing and transporting electricity.