How does reflection affect the intensity of the microwave?

[Cocoleia]

Homework Statement

I am working on a lab report, and I am a bit stumped at these questions:
How does reflection affect the intensity of the microwave? Is all the energy of the wave striking the Reflector reflected? Does the intensity of the reflected signal vary with the angle of incidence?

The Attempt at a Solution

I am trying to reason the answers using my logic and knowledge;
I would say that reflection would increase the intensity of the microwave. Since if there was light going to my receiver at a direct path and some that would reach after reflection, they would have a phase difference. Their combined intensity depends on this phase difference. This way could double what you would normal capture at the receiver.

For the energy, I would say yes. In this case, there is no refraction. Therefore since we must have conservation of energy, all of the energy of the wave that hits the reflector must be reflected as well. This answer, I am really unsure of. I don't get the concept of "reflected energy", I suppose.

For this, I am also unsure. I would say that it does vary. At larger angles of incidence, there is more of a chance of a part of the wave being lost and not reflected so the intensity would be less.

Can someone correct the errors in my logic and explain to me the proper concepts that I am missing? Thank you !

 

[CWatters]

I assume you did experiment 2 in here (or something similar)...
http://web.physics.ucsb.edu/~phys128/experiments/microwave/microwave.pdf

I would say that reflection would increase the intensity of the microwave. Since if there was light going to my receiver at a direct path and some that would reach after reflection, they would have a phase difference. Their combined intensity depends on this phase difference. This way could double what you would normal capture at the receiver.

I think you misunderstand the question. It's not about interference. They are asking what does the process of reflection do to the signal? Does it amplify it, attenuate it or leave it unchanged? The path length between transmitter and receiver was probably about the same for the direct case and the reflected case so any difference would be due to the process of reflection.

For the energy, I would say yes. In this case, there is no refraction. Therefore since we must have conservation of energy, all of the energy of the wave that hits the reflector must be reflected as well. This answer, I am really unsure of. I don't get the concept of "reflected energy", I suppose.

When you drop a ball on the floor it hits the floor with some velocity. The kinetic energy it has just before impact is KE=0.5mv². Does it have exactly the same velocity when it starts back up? Exactly the same energy or was some lost in the collision?

When you did the microwave experiment how did the direct signal path compare with the reflected signal path?

Does the intensity of the reflected signal vary with the angle of incidence?

What does your data show?

 

[davenn]

I would say that reflection would increase the intensity of the microwave.

how could you say that ? ... think about your answer, then consider "where would the extra microwave energy be coming from ?"