Electromagnetic waves [simple one]

Click For Summary
SUMMARY

The discussion revolves around calculating the average energy density of a sinusoidal radio signal broadcast by KQED at a power of 316 kW, located 6.00 km from the antenna. The energy density is derived using the formula u = P / (c * a), where 'P' is power, 'c' is the speed of light, and 'a' is the area over which the wave spreads. Additionally, participants seek to determine the percentage contributions of the electric and magnetic fields to the total energy density, utilizing the equation u = 1/2 * ε * E² + 1/2 * μ * B² and the relationship between E and B for plane electromagnetic waves.

PREREQUISITES
  • Understanding of electromagnetic wave properties
  • Familiarity with the equations for energy density in electromagnetic fields
  • Knowledge of the speed of light (c) and its significance in wave propagation
  • Basic concepts of electric field (E) and magnetic field (B) relationships in plane waves
NEXT STEPS
  • Research the relationship between electric field (E) and magnetic field (B) in electromagnetic waves
  • Explore the derivation of energy density equations for electromagnetic fields
  • Learn about the implications of power distribution in radio wave broadcasting
  • Investigate the calculation of energy density in different mediums
USEFUL FOR

Students studying physics, particularly those focusing on electromagnetism, as well as educators and professionals involved in radio frequency engineering and signal transmission analysis.

cupcake
Messages
73
Reaction score
0

Homework Statement



Public television station KQED in San Francisco broadcasts a sinusoidal radio signal at a power of 316 kW. Assume that the wave spreads out uniformly into a hemisphere above the ground.


At a home 6.00 km away from the antenna, what is the average density of the energy this wave carries?

For the energy density in part (a), what percentage is due to the electric field?

For the energy density in part (a), what percentage is due to the magnetic field?

Homework Equations



u= P/ (c*a)

u=1/2*epsilon* E^2 + 1/2mu * B^2

The Attempt at a Solution


i managed to do part A, by using equation u=P/(c*a)

i don't know how to get the percentage,, please advise
 
Physics news on Phys.org
The equation for the energy density you have quoted is a good starting point. To find the required percentage, you need to have a relation between E and B for plane EM waves. Can you think of one?
 

Similar threads

Electromagnetic waves radiating away from a transmitting tower
  • · Replies 3 ·
Replies
3
Views
2K
How an oscillator creates electromagnetic waves
  • · Replies 2 ·
Replies
2
Views
3K
An Electromagnetic wave goes from air into a medium....
  • · Replies 3 ·
Replies
3
Views
3K
Doubts on Exercise Wording: Energy Density & Poynting Vector
  • · Replies 1 ·
Replies
1
Views
1K
Superposition of two one-dimensional harmonic waves
  • · Replies 10 ·
Replies
10
Views
2K
Undergrad Momentum in electromagnetic waves
  • · Replies 1 ·
Replies
1
Views
2K
Graduate How to show spin ##= \pm 2/\omega## for a circ-polarized gravity wave
  • · Replies 0 ·
Replies
0
Views
2K
Understanding Electromagnetic Waves in a Vacuum
  • · Replies 4 ·
Replies
4
Views
2K
Sinusoidal electromagnetic wave help
  • · Replies 2 ·
Replies
2
Views
8K
How Does an Electromagnetic Wave Propagate in Glass?
  • · Replies 3 ·
Replies
3
Views
2K