Why does atoms in a conductor heat up when gaining enegry from electric charges?

[Sigmarus]

Thanks!

[Sensei]

Why does atoms in a conductor heat up when gaining enegry from electric charges?

 

Electrons decelerate, lose part of their kinetic energy, while passing through medium-conductor.

If they fly through other medium f.e. gas, they also lose their kinetic energy, it's visible by naked eye in Cloud Chamber particle detector.

Electrons accelerated to different velocities, will leave traces with different lengths. The more they were accelerated, the longer trace.