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Chapter 29: Problem 12

Electromagnetic waves don't readily penetrate metals. Why not?

Short Answer

Expert verified
Electromagnetic waves don't penetrate metals because the free electrons available in metals absorb the electromagnetic waves and convert their energy into heat or other forms, and because of this absorption, the waves are reflected instead of being transmitted through the metal.

Step by step solution

01

Understanding Electromagnetic Waves

Electromagnetic waves consist of oscillating electric and magnetic fields. They are capable of travelling through space where they can interact with matter, getting absorbed, reflected or transmitted.
02

Behavior of Metals under Electromagnetic Waves

Metals have a 'sea' of free moving electrons. When an external electromagnetic wave hits a metal, these free electrons oscillate with the electromagnetic field of the wave.
03

Absorption of Electromagnetic Waves

As these free electrons move, they collide with the metal's atoms, converting the kinetic energy into other forms, mainly heat. This process absorbs the energy of the electromagnetic wave, meaning it can't pass through. The wave is therefore reflected.
04

Conclusion

Therefore, electromagnetic waves don't readily penetrate metals because their energy is absorbed by the free-moving electrons found in the metal. This causes the wave to be reflected instead of transmitted through the metal.

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Most popular questions from this chapter

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A cylindrical resistor of length \(L\), radius \(a\), and resistance \(R\) carries current \(I\). Calculate the electric and magnetic fields at the surface of the resistor, assuming the electric field is uniform over the surface. Calculate the Poynting vector and show that it points into the resistor. Calculate the flux of the Poynting vector (that is, \(\sqrt{S} \cdot d \vec{A}\) ) over the resistor's surface to get the rate of electromagnetic energy flow into the resistor, and show that the result is \(I^{2} R .\) Your result shows that the energy heating the resistor comes from the fields surrounding it. These fields are sustained by the source of electric energy that drives the current.
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