How do electric and magnetic waves affect each other?

AI Thread Summary
A stationary charge generates an electric field, described by E = kq1q2/r^2, while a moving charge produces both an electric and a magnetic field, with the magnetic field given by B = ui/(2pi)r. The interaction between changing electric and magnetic fields is explained by Maxwell's equations, which require an understanding of vector analysis. A changing magnetic field induces an electromotive force in a closed loop, leading to current, which in turn creates a varying magnetic field. This cyclical relationship between electric and magnetic fields is fundamental to the behavior of electromagnetic waves.
MCATPhys
Messages
58
Reaction score
0
I understand that a stationary charge has an electric field by the equation:

E = kq1q2/r^2

When the charge starts to move, it has an electric field and a magnetic field:

B = ui/(2pi)r

where i is the current and u the permeability of free space. What I don't understand is the cause of electromagnetic waves. More specifically, how does a changing magnetic field cause a change in electric field, and a changing electric field cause a change in the magnetic field. I don't understand how. Can someone show it to me using the eqations.
 
Physics news on Phys.org
The behaviour of electromagnetic waves is governed By Maxwell's equations. You need to know vector analysis to fully understand this. There are some good video lectures on the topics, for example that of dr Lewin's: http://videolectures.net/mit803f04_lewin_lec13/

If you are not familiar with curl and divergence yet, keep in mind that electric field causes current, current causes magnetic field. In a changing magnetic field, there will be electromotive force in a closed loop. This causes current of some kind. If the current varies with time, it causes varying magnetic field around the loop and so on.

Be patient, you will learn about it soon!

ehild
 
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
Back
Top