Recent content by mondo

In reading chapter 6.1.2 I stumbled upon a magnetic torque concept which I don't understand, here is the problematic fragment In the formula for N author multiplies by ##sin(\theta)## but why? The torque is said to be caused by forces (caused by magnetic field) on opposite side of a...

heh right, thank you (and everyone involved) for a lesson .

Okay but this is true for any charge in any configuration - a location of its own electric field is undefined, right? However a direction and magnitude of an electric field from this charge to any other (test) charge is well defined and given by Coulomb's law.

@jtbell , I understand the problem is that the charge is moving, but we can describe its position quite accurately as it moves along x axis - it's just f(x) = 0; So I think if we express both charges position in some way then we can always calculate the distance between them and hence the...

It is a good point. The electric field I think is well defined - it needs to point away from both charges at they both repeal each other, right? As for the magnetic field, it is supposed to curl around the x axis as the charge is moving. Both direction are also mentioned by the author on the...

Yes the 'not' seems to be wrong there, but this post helped me to catch my main problem - I initially thought that Fm at point q1 is there due to the magnetic force generated by q1 itself. While this is a force in response to the magnetic field of charge q2 alone. Thank you all again for the...

But why in the direction of B2 if I want to establish magnetic field and magnetic force of q1? Also, the magnetic field is curling around the wire, so if I curl my palm and fingers respectively and follow the magnetic field trajectory then yes at some point (assuming I can do it anatomically) my...

How is that possible? The charge moves to the left so below picture describes the situation: So the thumb point in the direction of the charge q1, the magnetic field is into the page, but the magnetic force points down. The same rule applies to charge q2, and there it is ok, I only don't get...

@Orodruin , I am talking about the Fm that is pointing upwards from charge g1 - how can it be upwards? The charge is moving to the left hence the palm rule says the magnetic force is pointing downwards.

I am reading chapter 8th of Griffiths' electrodynamics (4th edition) on page 361 I stumbled upon this: For figure 8.3 I don't understand why does the magnetic force of charge q1 points upward? According to right hand rule the thumb should point in the direction of v1 and then fingers curling...

@Doc Al , it sort of makes sense however, isn't the electric field above and below the gaussian pillbox generated by the surface charge on the surface? Therefore it should be the same below, above and on the surface. And even if there are other changers in the space above or below the surface of...

So does the equation 2.31 mean - we expect this field to be zero (left hand side of the equation) but it needs to be $$\frac{1}{\epsilon_0}\sigma $$ (right side of the equation) because of the presence of the surface charge?

Hi, While reading griffith introduction to electrodynamic I have stumbled upon this: I don't understand why when the pillbox hight goes to zero we have a discontinuity of electric field. On the figure 2.36 we can see the electric field penetrates the surface from below the plane and exits...

Thanks for a repones. As for the first part about the small angles - yes I think I got it. Thanks for mentioning the assumed position is horizontal - that helped me to visualize the movement. As for the second derivative derivation, what is the last term in your formula -O(\Delta z^2). ? I...

I continue my reading of Griffiths electrodynamics (chapter 9, electromagnetic waves) and I got stuck on this: Author tries to prove a stretched string supports wave motion and I found it very difficult to grasp. In the second equation, why can we replace sin function with a tangents really...