Energy Carried by Electromagnetic Waves
Practice!
| Practice 13.4.1 |
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| A small source radiates an electromagnetic wave with a single frequency into vacuum, equally in all directions. As the wave propagates, its intensity: |
| Practice 13.4.1 |
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| What is the average magnitude of the Poynting vector 13 km from a radio transmitter broadcasting isotropically (equally in all directions) with an average power of 200 kW? |
Discuss!
What is the approximate magnitude of the electric field on a page if you are reading a book outdoors under the shade of a tree and happen to leave the book on the ground where the Sun shines on it? The intensity of sunlight reaching the surface of the Earth is about 1000 W/m2.
A fusion reactor focuses 2×1013 watts of x-rays on this deuterium capsule for 5 nanoseconds.
(a) What is the average energy density of the radiation?
(b) What is the electric field amplitude of the radiation?
Physics Education Research at UNG 