JOULE'S
LAW


INTRODUCTION:
_{
}
_{ }_{www.citycollegiate.com} When an electric current passes through a wire heat energy is produced. It is due to the collision of electrons with the atoms. In order to continue steady current, work has to be done on electric charges. 

STATEMENT: Amount of work done on electric charge on steady current is directly proportional to amount of heat. 

Work
a Heat


PROOF:  
Consider a conductor through which electric current q is passing in time t let the potential difference between two ends of wire is V.  
We know that  
v
= W/q
or W = q x V_(i) According to Ohm’s law V = IR putting the value of V in equation (i) W = q x IR_______(ii) 

But
I = q/t Or Q = It 

putting the value of q in equation (ii)  
W
= It . IR
W = I^{2}Rt 

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INTRODUCTION

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Ohm’s law is a quantitative relation b/w potential difference and electric current.  
STATEMENT


According to Ohm’s law,  
"The
electric current passes through a conductor is directly proportional
to the potential differences between the ends of conductor, if physical conditions of conductor remain constant." 

i.e.  
I
a V
I = kV 

K =constant and is called "conductivity of material"  
I/K
= V
or V = I/K V = I x 1/K Let [1/K = resistance] 

V
= I x R


GRAPHICAL
REPRESENTATION

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