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Ch 31: Electromagnetic Fields and Waves
Knight Calc - Physics for Scientists and Engineers 5th Edition
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796당신이 사용하는 게 아니라요?교과서 변경
모든 교과서Knight Calc 5th EditionCh 31: Electromagnetic Fields and Waves문제 42b
31장, 문제 42b

What is the total energy density in an electromagnetic wave of intensity 1000 W/m2?

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Understand the relationship between the intensity \( I \) of an electromagnetic wave and its energy density \( u \). The formula is \( I = c \cdot u \), where \( c \) is the speed of light in a vacuum (approximately \( 3 \times 10^8 \; \text{m/s} \)).
Rearrange the formula to solve for the energy density \( u \): \( u = \frac{I}{c} \).
Substitute the given intensity \( I = 1000 \; \text{W/m}^2 \) into the formula: \( u = \frac{1000}{c} \).
Use the value of \( c = 3 \times 10^8 \; \text{m/s} \) to rewrite the equation: \( u = \frac{1000}{3 \times 10^8} \).
Simplify the expression to find the energy density \( u \). This will give you the total energy density in \( \text{J/m}^3 \).

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주요 개념

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Energy Density in Electromagnetic Waves

Energy density in electromagnetic waves refers to the amount of energy stored in a given volume of space. It is typically expressed in joules per cubic meter (J/m³) and is a crucial concept for understanding how energy propagates through electromagnetic fields, such as light.
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가이드 코스
05:22
Introduction to Electromagnetic (EM) Waves

Intensity of Electromagnetic Waves

Intensity is defined as the power per unit area carried by an electromagnetic wave, measured in watts per square meter (W/m²). It quantifies how much energy is transmitted through a surface perpendicular to the direction of the wave's propagation, and is directly related to the energy density of the wave.
추천 영상:
가이드 코스
02:32
Wave Intensity

Relationship Between Intensity and Energy Density

The relationship between intensity (I) and energy density (u) in an electromagnetic wave is given by the equation I = (1/2) * c * u, where c is the speed of light in a vacuum. This relationship allows us to calculate the total energy density from the intensity of the wave, providing a direct link between these two important concepts.
추천 영상:
가이드 코스
03:43
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