Electrical impedance is a measure of the opposition of an electrical circuit to the flow of alternating current. Synonyms for electrical impedance include resistance, reactance, impedance magnitude, phase angle, and admittance. Resistance, which is measured in ohms, represents the opposition to the flow of electrical current in a direct current circuit. Reactance refers to the opposition to the flow of alternating current and is typically measured in ohms as well. Impedance magnitude represents the total opposition to the flow of alternating current in an electrical circuit, including both resistance and reactance. Phase angle, measured in degrees, represents the difference in timing between the voltage and current waves. Finally, admittance is the inverse of impedance, representing the ease with which a circuit allows the flow of current.