This is a simple circuit i found on web. Please explain how it works as easy as possible. I want to know how transistor is generating the frequency in transmitter.
It's basically a circuit that generally falls under the umbrella "joule thief": -
The LED is not needed to make it oscillate just to demonstrate that an LED can be lit from a depleted 1.5 volt battery even though the LED needs about 2 volts to make it shine. In other words it extracts (or thieves) the last few joules of energy from a battery thus allowing an LED to shine for a longer.
So, in the absense of the LED it is still an oscillator.
Here's wikipedia's answer and there are literally hundreds of sites out there with the same explanation so. now you have the name you can choose the site that suits your level of understanding. Get googling!
The magnetic energy created by the transmitting oscillator leaks out across space and can be received by another coil and a terminal voltage is produced. If the receive and transmit coils are close enough an LED can be lit.
The transmitter creates a moving (AC) magnetic field in the coil. The receiver pickups some of that magnetic field in its coil.
The wireless electricity acts like magnetic induction, similar a transformer that transfers electrical voltage across a condutor but they use alternating current (AC).
The transmitter have unidirectional flow of current, like a battery. For that reason, the circuit have a simple oscillator known for Hartley oscillator.
I hope I have helped your study.