# Sinusodial solution of EM equation

1. Oct 30, 2007

### pardesi

what kind of sources of light generate sinusodially varying electric field that is solutions of the form
$$E(x,t)=E_{o}(x,t) \sin(kx-\omega t)$$

2. Oct 30, 2007

### clem

All light sources do.

3. Oct 30, 2007

### sokratesla

# Radiation needs "sinusodially varying electric field" For example, if a charged particle makes an oscillation in space, its electric field makes and an oscillation with a delay in time, according to the distance of the field point to the source.
# And light is an EM radiation (which is visible.) So by definition every kind of light sources generate oscillating E fields.

4. Oct 31, 2007

### pardesi

ues they do generate oscillating field but point sources generate spherical waves which are not sinusodial since they are inversely propotional to distance

5. Oct 31, 2007

### Meir Achuz

The extra spatial dependence is in the E_0(r,t) in the original post.

6. Oct 31, 2007

### ZapperZ

Staff Emeritus
Then you need to be more specific and clearer in your question. Recalled that you asked about sources of light, and by "light", we automatically associated EM wave, not static E-field in electrostatics situations.

So you have to figure out exactly what it is here that you want, and ask accordingly.

Zz.

7. Nov 1, 2007

### pardesi

sorry i meant solutions of the form $$E(x,t)=E_{0}\sin(kx-\omega t)$$

8. Nov 1, 2007

### Claude Bile

We need to work in 3D if we want to talk about real sources.

$$E(r,t)=E_{0}\sin(k.r-\omega t)$$

Is an infinite plane wave, no real source can produce such a wave.

It is possible however to express a propagating wave of arbitrary spatial shape as a linear sum of plane wave components, much the same way we can describe a wave with an arbitrary shape in time as a linear sum of discrete sinusoidal frequencies.

Claude.

Last edited: Nov 1, 2007