# Impedence and Resistance

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#### nemolee

##### Full Member level 3
Hi,

What different are they between impedence and resistance?
thanks.

#### tara1

##### Newbie level 2
h**p://www.teamrocs.com/technical/pages/resistance_impedance.htm

resistane contains only R.
but impedance can contains R , L , C

#### sip

##### Junior Member level 1
Resistance :
Cause of the resistance is the arrangement of the atomic structure in the element which causes trouble for the flow of electrons. ie., when the electrons moves from higher voltage level to lower voltage level it will steadily lose its energy by colliding with the atoms that came across the way towards the lower voltage level.
So this is called the resistance.

Eg:
Let us take a small rock rolling down a hill. It may reach the valley depending upon the number of obstacles in its path. If there are many ostacles then resistance offered in that path is high so only less number of rocks rolling down will reach the valley for the same height when compared to another way which provide less obstacles. Similarlly in electrical when the resistance offered by the path is high then the current (number electrons following ) will reduce.

Impedence :
It is one kind of transducer which changes the current or voltage into magnetic or electric field.
Inductor converts current into magnetic field while the capacitor converts the voltage into electric field. So the converting factor place an important roll in its reactance which offer no power loss. But there may be some resistance in these elements which offer power loss. So in general reactance offer no power loss while resistance do. Impedance is the combination of both reactance and resistance

#### a_aziz

##### Member level 3
hi.
resistance is real. impedance is complex.
resistance is one part of impedance.

#### suvendu

##### Full Member level 3
in ac theory,in general we say voltage divided by current is called impedance.ie it may be pure resistive,inductive or capacitative.impedane is a general term but resistance is specific.

#### gupta

##### Junior Member level 1
ac circuits::
impedence:
total opposition in flow of current in a circuit.
Z= V/I
Resistance:
real component of impedence. it is situated at zero degree from applied voltage.

#### electron_boy

##### Full Member level 3
resistance is real and impedance is complex. in resistive devices the current is in phase with the voltage while in L C circuits the current may lead or lag the voltage according to the impedance (X+jy) or (X-jy)

#### krishna_y

##### Newbie
resistance is dc quantity it is real but where as the impedence is ac quantity which is complex.impedence contains both resistance and the reactance .reactance is due to the inductance and capacitance effects.

#### sabari

##### Member level 3
Resistance :
Cause of the resistance is the arrangement of the atomic structure in the element which causes trouble for the flow of electrons.
Impedence :
It is one kind of transducer which changes the current or voltage into magnetic or electric field.

resistance is real. impedance is complex.

#### awan

HELLO
impedence is related to the opposition which device does for the ac signal and the resistance is the name given for the opposition causedfor DcC signals. If u want t know more about it please read the book "BASIC ENGINEERING CIRCUIT ANALYSIS BY DJ IRWIN" FIFTH EDITION CHAPTER NO 9

#### power-twq

##### Full Member level 6
resistance is R;

impedance is R and j(2*PI*f)*L and 1/(j (2*PI*f)*C)

best regards

nemolee said:
Hi,

What different are they between impedence and resistance?
thanks.

#### checkmate

Impedence is simply Z=V/I. Period. It's really just the ratio of voltage against current, nothing too complicated.

For elements that follow Ohm's Law, ie ohmic conductors aka resistors, Z is a real constant number, and Z is replaced by R to give you Ohm's Law of R=V/I. So Ohm's Law is really just a special case of the definition of impedence.

#### userdce

##### Member level 2
ya i agree with aswrs above

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