Answer / dolphin

generally different conductors are having different
electron density.if current flows from high
electron density conductor to low density conductor
heat will be produced at the junction due to sudden
change in electron density.to avoid this the two
conductors to be junctioned should have minimum
difference in electron density.in some other cases
contact resistance causes heat if they are not
tightly held together.

Answer / kapil gehlot

when two conductor are joined then a contact resistance is
genrated due to that heat is generated and second reason
would be change of electron density and chnage of
resistivity.

Answer / amol

current passes from one conductor to another conductor, if
cross section area is less then it will take heating of
conductor

Answer / ayub

Because of losses due to the collission of electrons and
also due to the diffrent condutors the metal are diffrent
so losses will take place when passing through the one
conductor to the another diffrent conductor.

Answer / pradeep kumar rawat

at the junction of two conduntor some gap are formed at the
junction point, due to this gap some air take place and
ionised by other ions which is flowing in two conductor,air
between two conductor ionised and current posses through
one conductor to other conductor and heat produces, due to
this at the junction of two conductor heat produced.

Answer / ashwin

The two dissimilar metals behave or contribute a thermocouple. A thermocouple is a junction between two dissimilar metals when subjected to heat generates voltage. This is seebeck effect. The inverse of this effect is Peltier effect. When current is passed through a junction containing two dissimilar metals heat is generated.

For more details on the principle of thermocouple go to link below:

http://en.wikipedia.org/wiki/Thermocouple

From the above link if you can reverse the effects or its causative factors you can minimize this effect.

Answer / aziz_raghib2002

at the junction of the two conductors the conductors will
have different potential due to thier material
characteristics and thats why some P.D and so currentand
heat ie cu losses same material should be used and same
ch/hs material

Answer / naveen gupta

Two different metals have two different conductivity, so
the movements of electrons get obstructed during this
transition. Thats why the heat get generated.

Now to minimize it we need to increase the surface area
depending upon their conductivity levels.

Answer / vishnu p jariwala

Both conductors have differend impedance(Z),And Becose of
resister heat losses is accour That's why...

Answer / j.kesavan

we are use different conductors ,suppose we joint copper and
aluminium busbars using bimetalstrip reduce heat.

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