In an RL circuit, which consists of a resistor (R) and an inductor (L) in series, the impedance \( Z \) is given by a combination of the resistance and the inductive reactance.
The formula for the impedance \( Z \) in an RL circuit is:
\[ Z = R + jX_L \]
where:
- \( R \) is the resistance of the resistor (in ohms, Ω).
- \( j \) is the imaginary unit (equivalent to \(\sqrt{-1}\)).
- \( X_L \) is the inductive reactance of the inductor (in ohms, Ω).
The inductive reactance \( X_L \) is calculated using:
\[ X_L = \omega L \]
where:
- \( \omega \) (omega) is the angular frequency of the AC source (in radians per second), given by \( \omega = 2 \pi f \), where \( f \) is the frequency in hertz (Hz).
- \( L \) is the inductance of the inductor (in henries, H).
So, combining these, the impedance \( Z \) can also be expressed as:
\[ Z = R + j(\omega L) \]
In this representation:
- The real part of \( Z \) is the resistance \( R \).
- The imaginary part is the inductive reactance \( \omega L \).
The magnitude of the impedance \( |Z| \) can be found using:
\[ |Z| = \sqrt{R^2 + (\omega L)^2} \]
This magnitude represents the overall resistance to current flow in the RL circuit when subjected to an alternating current (AC) signal.