JOULE'S LAW
 
 
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    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 Ohmís 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 = I2Rt
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OHM'S LAW
INTRODUCTION
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    Ohmís law is a quantitative relation b/w potential difference and electric current.
STATEMENT
 
    According to Ohmís 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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