Deriving wave eqn. from Faraday & A.M.

In summary, the conversation discusses deriving the equation for the magnetic field, B, in the form of del2B = 1/c2 * d2B/dt2 starting from Faraday's Law and Ampere-Maxwell Law. The attempt at a solution involves taking the curl of both sides of A.M and using Faraday's Law to simplify the expression. The conversation ends with a question about the substitution for curl E resulting in -ε0μ0 d2B/dt2 instead of -ε0μ0 dB/dt.
  • #1
Roodles01
128
0

Homework Statement


I'm asked to start from Faradays Law & Ampere-Maxwell law then derive the equation for the magnetic field, B, in the form;

del2B = 1/c2 * d2B/dt2



Homework Equations


Faraday: curl E = -dB/dt
A.M : curl B = ε0μ0 dE/dt


The Attempt at a Solution


taking curl of both sides of AM

rhs
curl curlB = grad div B - del2B
no monopole says divB = 0
so = - del2B

lhs
curl curl B = ε0μ0 curl dE/dt
rearrange
= ε0μ0 d/dt curl E
Faraday says curl E = -dB/dt

in the next step of working out I don't get why this goes to
-ε0μ0 d2B/dt2
instead of
-ε0μ0 dB/dt

Addled, I must be [Yoda]
 

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  • #2
[itex]-\nabla ^2 \mathbf{B} = \epsilon_0 \mu_0 \frac{\partial}{\partial t}\nabla \times E[/itex]

Try the substitution for [itex]\nabla \times E[/itex] again.
 
  • #3
Thank you.
Nose - Face - well known phrase.
 

1. How is the wave equation derived from Faraday's law and Ampere's law?

The wave equation can be derived by combining the mathematical expressions for Faraday's law and Ampere's law. Faraday's law states that the induced electromotive force (EMF) is equal to the rate of change of magnetic flux through a surface. Ampere's law states that the magnetic field around a closed loop is proportional to the current passing through the loop. By combining these two laws, we can derive the wave equation, which describes the propagation of electromagnetic waves through space.

2. What is the significance of deriving the wave equation from Faraday's law and Ampere's law?

Deriving the wave equation from Faraday's law and Ampere's law allows us to understand the fundamental principles behind the propagation of electromagnetic waves. It also helps us to make connections between different phenomena and laws in electromagnetism, and provides a deeper understanding of how electromagnetic fields behave.

3. Are there any assumptions made when deriving the wave equation from Faraday's law and Ampere's law?

Yes, there are a few assumptions that are made when deriving the wave equation from Faraday's law and Ampere's law. These include assuming that the medium in which the electromagnetic waves are propagating is linear, isotropic, and homogeneous.

4. How is the wave equation used in practical applications?

The wave equation is used in a wide range of practical applications, such as in the design and analysis of antennas, communication systems, and electromagnetic wave propagation in different media. It is also used in the field of optics to understand the behavior of light and other electromagnetic waves.

5. Can the wave equation be derived using other laws or principles?

Yes, the wave equation can also be derived from Maxwell's equations, which are a set of four fundamental equations that describe the behavior of electric and magnetic fields. Additionally, the wave equation can also be derived from the principles of conservation of energy and momentum. However, deriving it from Faraday's law and Ampere's law is a more intuitive approach, as it directly relates to the physical processes involved in the propagation of electromagnetic waves.

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