Why stationary charges and constant currents do not produce electromagnetic waves?

Lochan Chandra Gupta    June 25 2022 02:48:14 PM

Ans

Arpita Singh    June 16 2025 02:50:53 PM

Stationary charges don’t produce electromagnetic waves because they’re not moving, so they only create an electric field, not a changing one.

Constant currents do create both electric and magnetic fields, but since they’re steady and not changing with time, there’s no variation to cause the fields to ripple outward as a wave.

Electromagnetic waves are only produced when charges accelerate or when currents change — like in an antenna where the current keeps going back and forth.

That changing motion is what actually generates the waves that travel through space.

Anjali Sharma    June 16 2025 02:51:55 PM

Yeah, jumping in here — the key thing is that electromagnetic waves are created when electric and magnetic fields change with time.

A stationary charge just sits there, so its electric field doesn’t change, and there's no magnetic field at all.

And with a constant current, even though there’s a magnetic field, it’s steady — not changing. Since both the electric and magnetic fields are constant, there’s nothing to “disturb” the space around them and send out waves.

You need some kind of acceleration or variation for EM waves to be generated.

Manjesh    June 16 2025 02:53:31 PM

Hey, mind if I jump in too?

So, basically, for electromagnetic waves to be produced, the electric and magnetic fields have to be changing with time.

A stationary charge just creates a static electric field — nothing’s moving, so nothing’s changing. And a constant current creates a steady magnetic field, but again, it's not changing.

Since electromagnetic waves come from time-varying fields, neither of these situations has what it takes to generate them.

You only get EM waves when charges accelerate or currents vary, like in AC circuits or antennas.

Anchal Singh    June 16 2025 02:57:38 PM

Hey everyone! Just adding my thoughts — electromagnetic waves are all about changing electric and magnetic fields. A stationary charge doesn’t move, so its electric field just stays the same — no wave.

And with a constant current, the magnetic field is there, but it’s steady, not changing over time. Since there’s no time variation in either case, there’s nothing to create or carry energy away as a wave.

You only get electromagnetic waves when there’s acceleration or changes happening in the fields.

That’s when the energy actually starts radiating out into space.