Why current flow from drain to source in JFET?

In a Junction Field-Effect Transistor (JFET), current flows from the drain to the source due to the application of a voltage between these terminals, creating an electric field that allows charge carriers (electrons for n-channel JFETs or holes for p-channel JFETs) to move through the channel. The gate voltage controls the channel's conductivity by modulating the width of the depletion region, which affects the flow of charge carriers. When the drain-source voltage (V_DS) is applied, it causes electrons to flow from the drain to the source in an n-channel JFET, completing the circuit. The flow direction is thus determined by the polarity of the applied voltages and the type of semiconductor material used.