Why does DC current not generate EMR?

[suhasm]

During current flow , electrons are certainly being accelerated and decelerated betweeen two successive collisions with the metal lattice. Since accelerated charge generates EM waves , why doesn't a DC current emit EMR?

 

[mkillman]

heat is a form of magnetic radiation

Pass DC voltage thru a wire and heat is the byproduct

 

[willem2]

During current flow , electrons are certainly being accelerated and decelerated betweeen two successive collisions with the metal lattice. Since accelerated charge generates EM waves , why doesn't a DC current emit EMR?

The drift speed of electrons is incredibly slow compared to the random motions of the electrons. The drift speed is less than a millimeter per second, compared to hundreds of meters per second, for the so the drift speed will make no measurable contribution to the accelerations of the electrons.

The accelerations of electrons will always cause electromagnetic radiation, and this depends only on the temperature and not on the the presence of current. Until the material becomes so hot it starts to glow, the radiation will be infrared radiation.

Of course, the current can heat up the material, that will then radiate more infrared.

 

[Drakkith]

heat is a form of magnetic radiation

Pass DC voltage thru a wire and heat is the byproduct

Heat is not a form of EM radiation. It is the random motion of particles in a material. EM radiation can be converted to heat upon being absorbed though.

 

[sardar]

DC current does generate electromagnetic radiation (EMR), but the amount of EMR emitted is significantly lower compared to alternating current (AC). This is because in DC current, the direction of the current remains constant and there is no change in the direction of the flow of electrons. This means that the acceleration and deceleration of electrons between collisions with the metal lattice is also constant. In order to generate significant amounts of EMR, the acceleration of electrons must vary, which is the case in AC current where the direction of the current changes constantly. This results in a continuous generation of EM waves. In DC current, the acceleration of electrons is not enough to produce significant amounts of EMR, thus making it less detectable. However, it is important to note that even in DC current, there is still some level of EMR being emitted, but it is not strong enough to be detected by most instruments.