# Effect of varying magnetic field on a static charge

1. Dec 6, 2014

### arul_k

I would like to know if any experiments have been conducted to determine the effect of a time varying magnetic field on a static electrically charged object.

If so, are they any links to these experiments on the web

Thanks.

2. Dec 6, 2014

### Staff: Mentor

Nearly every setup in electromagnetism has this in some frame for some moment in time. The variable magnetic field always comes with electric fields, and only those influence the particle (in the frame where it is at rest).

3. Dec 7, 2014

### arul_k

I am aware that the electric field created by the varying magnetic field would effect a charged particle.

What I wish to know is if any experiments have been specifically conducted to observe the effect of the electric field created by a varying magnetic field on a charged object/particle.

4. Dec 7, 2014

### Staff: Mentor

Every motor does that.

And sure, the Maxwell equations have been tested in thousands of experiments.

5. Dec 8, 2014

### arul_k

Could you explain what you mean by every motor does that. Specifically, which experiment has been performed to test the effect of a time varying magnetic field on a static charge?

6. Dec 8, 2014

### Staff: Mentor

Every motor has a time-varying magnetic field, and charges that do not move (at zero current) or do not move in a significant way (at typical currents) or do not move in a suitable reference frame (moving together with the charges).
All basic experiments about electromagnetism do, including "move a magnet close to a conductor" in every possible way.

7. Dec 9, 2014

### arul_k

Thanks mfb for your reply. I wasn't refering to induction due to a varying magnetic field. As I mentioned in my first post, I wish to know the effet of the varying magnetic field on an electrostatically charged object.

8. Dec 9, 2014

### Staff: Mentor

The induced emf which causes electrons to move in a wire, in electromagnetic induction, is the direct result of the $\vec E$ field which is associated with a changing $\vec B$ field. By definition, emf is the line integral of $\vec E$. The usual equation for induced emf, $$\mathcal{E} = - \frac{d\Phi_B}{dt}$$ is equivalent to $$\oint {\vec E \cdot d \vec l} = \frac{d}{dt} \int {\vec B \cdot d \vec a}$$ which in turn leads (via Stokes's Theorem) to $$\vec \nabla \times \vec E = - \frac{d \vec B}{dt}$$

9. Dec 9, 2014

### Staff: Mentor

Electrons have an electric charge, and if they are free (in vacuum or in metals) you could even call them "electrostatically charged objects".