The Transfer Function of Low-Pass RL Filter is:

The correct answer is option 4): \(\frac{{{V_{out}}}}{{{V_{in}}}} = \frac{1}{{1 + j\omega L/R}}\)

Concept:

• A low-pass RL filter, again, is a filter circuit composed of a resistor and inductor which passes through low-frequency signals, while blocking high-frequency signals.
• To create a low pass RL filter, the inductor is placed in series with the input signal and the resistor is placed in parallel to the input signal, such as shown in the circuit below:
• 
• The transfer function of the Low-Pass RL Filter is

​\(\frac{{{V_{out}}}}{{{V_{in}}}} = \frac{1}{{1 + j\omega L/R}}\)