Anna University TNEA 2018 Rank List Published. Login to know your Rank. Anna University April May 2018 Exam Results Anna University Latest News , Updates and Announcements >>> Anna University Sixth Semester Question Bank Collection (R2013) ECE,MECH,CSE,IT,EEE,CIVIL,EIE >>> Anna University Study Materials for all Departments >>> Anna University Question Papers : April May June 2015 Question Papers | Nov Dec 2014 and Jan 2015 Question Papers

Register or Login to Submit Study Materials , Shoutbox and also to access Many Features !!

Resistance , Reactance , Impedance - Explanation

Resistance, R

Resistance is essentially friction against the motion of electrons. It is present in all conductors to some extent (except superconductors!), most notably in resistors. When alternating current goes through a resistance, a voltage drop is produced that is in-phase with the current.

Resistance is mathematically symbolized by the letter “R” and is measured in the unit of ohms (Ω).

Reactance, X

Reactance is essentially inertia against the motion of electrons. It is present anywhere electric or magnetic ﬁelds are developed in proportion to applied voltage or current. respectively; but most notably in capacitors and inductors. When alternating current goes through a pure reactance, a voltage drop is produced that is 90° out of phase with the current.

Reactance is mathematically symbolized by the letter “X” and is measured in the unit of ohms (Ω).

Impedance, Z

Impedance is a comprehensive expression of any and all forms of opposition to electron ﬂow, including both resistance and reactance. It is present in all circuits, and in all components. When alternating current goes through an impedance, a voltage drop is produced that is somewhere between 0” and 90° out of phase with the current.