Application of LC circuit(tank circuit)
In today's era of communication, all is going on digitally. Instead of using variable capacitor, people nowadays using Varactor Diode. See below figure.



Applied Voltage across D1 will result into change in capacitance value.


  Modern electronic tuners also use varactor diodes as the actual tuning elements, but the voltages which change their capacitance are obtained from a digital to analog converter (DAC) driven by a microprocessor or phase locked loop (PLL) arrangement. This modern form allows for very precise tuning and locking-in on weak signals, as well as a numerical display of the tuned frequency.