How Does Permittivity Affect Energy Transmission in EM Waves?

In summary, the problem involves a sphere with a radius of 50 cm in a nonmagnetic medium with a permittivity of 4. An EM wave with an amplitude of 200 V/m is spreading through the medium and the question asks how much energy passes through the surface of the sphere in 1 minute. The conversation brings up two possible solutions, one involving replacing ε0 with ε in a calculation and the other involving integrating over the entire sphere to find the total power. It is also mentioned that the sphere is made of a spherical volume within the dielectric with a permittivity of 4.
  • #1
diracdelta
55
0

Homework Statement


Sphere of a radius R=50 cm is in nonmagnetic medium of
permittivity ε=4. EM wave with amplitude of electric field Em= 200 V/m is spreading through the medium.
How much energy pass through surface of sphere through 1 minute?

I have couple of question here. Since the sphere is in nonmagnetic medium how will that reflects of her magnetic field?
She doesn't have one?

So here's next flow of mind.I thought of two possibilities.
1) Sav*A*T= ε0*c*E*T
Q: Should i replace ε0 with ε?
Calculating this is quite easy, not sure if correct.

2)
Lets integrate over whole sphere of radius R, to find total Energy/time, that is, total power.
P = ∫sphere Savg
this way is much longer as far as mathemathics, but in the end, it should turn out same.

Are both solutions good?
 
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  • #2
What is the sphere made of? Is it just a spherical volume within the e=4 dielectric, or metallic, or air, or ?
 
  • #3
Its just spherical volume within e=4.
 
  • #4
diracdelta said:
Its just spherical volume within e=4.
Consider integrating the poynting vector over the sphere's internal "great circle" cross-section.
 
  • #5


Both solutions are valid approaches to calculating the energy passing through the surface of the sphere in one minute. However, the first solution using the equation Sav*A*T= ε0*c*E*T is the more straightforward and efficient method. This equation takes into account the permittivity of the medium, which is necessary for accurately calculating the energy passing through the surface. In this case, you would use the value of ε (4) instead of ε0 in the equation.
 

Related to How Does Permittivity Affect Energy Transmission in EM Waves?

1. What is the relationship between energy and electromagnetic (EM) waves?

Electromagnetic waves carry energy through oscillating electric and magnetic fields. The amount of energy carried by an EM wave is directly proportional to its frequency, meaning that higher frequency waves have more energy than lower frequency waves.

2. How is energy distributed in an EM wave?

In an EM wave, energy is evenly distributed between the electric and magnetic fields. As the wave propagates through space, the energy is constantly exchanged between the electric and magnetic fields, maintaining a balance.

3. How does the energy of an EM wave change as it travels through different mediums?

The energy of an EM wave remains constant as it travels through different mediums. However, the speed and wavelength of the wave may change, which affects the frequency and energy density of the wave. In some cases, the medium may absorb some of the energy, causing a decrease in the intensity of the wave.

4. Can the energy of an EM wave be measured?

Yes, the energy of an EM wave can be measured through various methods, such as using a calorimeter or a photodetector. The amount of energy can be calculated using the equation E = hf, where E is energy, h is Planck's constant, and f is frequency.

5. How does the shape and size of an object affect the energy of EM waves?

The shape and size of an object can affect the energy of EM waves in several ways. For example, a larger object may reflect or absorb more energy than a smaller object due to a larger surface area. Similarly, the shape of an object can influence the direction and intensity of the EM waves it reflects or transmits.

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