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JOULE'S
LAW
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| 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. |
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| STATEMENT: Amount of work done on electric charge on steady current is directly proportional to amount of heat. |
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Work
a Heat
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| 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 | |||
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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) |
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But
I = q/t Or Q = It |
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| putting the value of q in equation (ii) | |||
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W
= It . IR
W = I2Rt |
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INTRODUCTION
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| Ohm’s law is a quantitative relation b/w potential difference and electric current. | |||
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STATEMENT
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| According to Ohm’s law, | |||
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"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." |
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| i.e. | |||
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I
a V
I = kV |
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| K =constant and is called "conductivity of material" | |||
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I/K
= V
or V = I/K V = I x 1/K Let [1/K = resistance] |
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V
= I x R
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GRAPHICAL
REPRESENTATION
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| For latest information , free computer courses and high impact notes visit : www.citycollegiate.com | |||