What is an AC circuit?
A circuit in which current changes direction periodically due to an alternating voltage.
What is the general form of AC voltage?
\( V = V_0 \sin(\omega t) \)
What is the peak voltage \( V_0 \)?
The maximum voltage value in an AC waveform.
What does \( \omega \) represent in AC equations?
Angular frequency: \( \omega = 2\pi f \)
What is instantaneous voltage in AC?
Voltage at any moment: \( V = V_0 \sin(\omega t) \)
What is the RMS voltage?
\( V_{\text{rms}} = \frac{V_0}{\sqrt{2}} \)
What is the RMS current?
\( I_{\text{rms}} = \frac{I_0}{\sqrt{2}} \)
How is peak voltage related to RMS?
\( V_0 = \sqrt{2} V_{\text{rms}} \)
How is peak current related to RMS?
\( I_0 = \sqrt{2} I_{\text{rms}} \)
Why are RMS values used in AC?
They represent equivalent DC values for power dissipation.
What is the phase relationship in a resistor-only AC circuit?
Voltage and current are in phase.
RMS current in resistor-only AC circuit?
\( I_{\text{rms}} = \frac{V_{\text{rms}}}{R} \)
Peak current in a resistor-only AC circuit?
\( I_0 = \frac{V_0}{R} \)
What is capacitive reactance \( X_C \)?
\( X_C = \frac{1}{\omega C} = \frac{1}{2\pi f C} \)
How does current behave in a capacitor in AC?
Current leads voltage by \( 90^\circ \)
RMS current for a capacitor?
\( I_{\text{rms}} = \frac{V_{\text{rms}}}{X_C} \)
Peak current for a capacitor?
\( I_0 = \frac{V_0}{X_C} \)
What is inductive reactance \( X_L \)?
\( X_L = \omega L = 2\pi f L \)
How does current behave in an inductor in AC?
Current lags voltage by \( 90^\circ \)
Voltage across an inductor?
\( V = I X_L \)
Impedance in RL circuit?
\( Z = \sqrt{R^2 + X_L^2} \)
Phase angle in RL circuit?
\( \tan \theta = \frac{X_L}{R} \)
Voltage relationship in RL?
\( V^2 = V_R^2 + V_L^2 \)
Impedance in RC circuit?
\( Z = \sqrt{R^2 + X_C^2} \)
Phase angle in RC circuit?
\( \tan \theta = \frac{X_C}{R} \)
Voltage relationship in RC?
\( V^2 = V_R^2 + V_C^2 \)
Impedance in LC circuit?
\( Z = \sqrt{|X_L - X_C|} \)
Phase relationship in LC circuit?
\( V_L \) and \( V_C \) are 180° out of phase.
Peak current in LC circuit?
\( I_0 = \frac{V_0}{\sqrt{|X_L - X_C|}} \)
Impedance in RLC circuit?
\( Z = \sqrt{R^2 + (X_L - X_C)^2} \)
Peak current in RLC circuit?
\( I_0 = \frac{V_0}{Z} \)
RMS current in RLC circuit?
\( I_{\text{rms}} = \frac{V_{\text{rms}}}{Z} \)
Reactance difference in RLC?
\( X = X_L - X_C \)
What is resonance in AC circuits?
It occurs when \( X_L = X_C \), and current is maximum.
Formula for resonance frequency \( f_0 \)?
\( f_0 = \frac{1}{2\pi \sqrt{LC}} \)
Impedance at resonance?
Minimum; \( Z = R \)
Maximum current at resonance?
\( I_{\text{max}} = \frac{V}{R} \)
Average power formula in AC?
\( P = IV \cos \phi \)
Power factor expression?
\( \cos \phi = \frac{\text{Resistance}}{\text{Impedance}} \)
Power in resistive load?
\( P = I^2 R \)
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