Electric heat generation.

[alpha2cen]

When electric current flows through the nichrome wire , heat is generated.

We know this phenomena macroscopically.

Then, at the microscopic level or atomic level, how the heat is created?

[swansont]

Electrons electromagnetically bouncing off other electrons and nuclei. The increased kinetic energy of their random motion is reflected by an increase in temperature.

[alpha2cen]

The nichrome wire makes electric potential difference, voltage is well known. But it is not clear the heat generation mechanism. How heat is generated between fast moving electron and the random moving electron. Microscopic heat generation mechanism between nichrome atom and fast moving electron is not clear.

Edited December 25, 2010 by alpha2cen

[Moontanman]

The heat is caused by resistance in the wire, some things conduct electricity better than others, if you force current through a resistant material you get heat.

[swansont]

The nicrome wire makes electric potential difference, voltage is well known. But it is not clear the heat generation mechanism. How heat is generated between fast moving electron and the random moving electron. Microscopic heat generation mechanism between nicrome atom and fast moving electron is not clear.

 

Collisions of the electrons with other electrons and nuclei. It increases the random motion (increase in KE)

[alpha2cen]

Let's do this experiment. 110volt commercial electric source. There are 3m nichrome wire heater, 2m nichrome wire heater and 1m nichrome wire heater. Which one produce the most much amount of heat? Among them 1m nichrome heat produces the most much amount of heat.

I think the difference is electric current(A)difference. Then, Why the copper wire part in the heater does not produce heat? Between copper and nichrome difference. What?

[swansont]

The difference between the copper and nichrome is the resistance. Nichrome's resistivity is about 60 times greater than copper's so if the wires are the same cross-section the resistance will be 60 times greater per unit length. Which means that the electrons will not lose as much energy in the copper, and it will heat up less.

 

The difference in the three lengths of wire is indeed the difference in current, which is dictated by the resistance.. P = IV and V = IR so P = V^2/R. The amount of power dissipated in the circuit drops as R increases, and R is proportional to the length.

[alpha2cen]

The problem is the other part of the line does not produce heat. Only a part of the nichrome wire produces heat energy. How does the flowing electrons interact with nichrome alloy molecules or near electrons?

 

 

[swansont]

The problem is the other part of the line does not produce heat. Only a part of the nichrome wire produces heat energy. How does the flowing electrons interact with nichrome alloy molecules or near electrons?

 

No, that's not true. All parts of a resistive circuit produce heat, in relation to their resistance. The electrons interact electrostatically.

[alpha2cen]

No, that's not true. All parts of a resistive circuit produce heat, in relation to their resistance. The electrons interact electrostatically.

 

The generated heat from copper wire region is very very small compare to nichrome wire region.

[swansont]

The generated heat from copper wire region is very very small compare to nichrome wire region.

 

Because the resistance is smaller.