Equipment:
-Cellphone
-Radio
-Shielding materials: plastic wrap, aluminum foil, paper, cloth
Procedure:
Wrap the cellphone or radio with shielding materials according to the questions asked.
Questions:
1) Experiment with wrapping your cell phone entirely in a variety of materials. Which materials blocked EM waves so that your phone could not receive call? What aspect of those materials caused them to successfully shield EM waves from the phone?
- The call went through the plastic wrap, paper, and cloth. The call was blocked when the cellphone was completely wrapped in aluminum foil. The aluminum foil creates a Faraday cage. This cage reduces the amount of electromagnetic radiation that passes to the cellphone, preventing the cellphone from receiving the call.
2) Based on your observations, what can you infer about elevators, tunnels, and other locations where shielding occurs.
- I can infer that elevators and tunnels will also block the cellphone call.
3) As a group, go to the elevator. Place one person inside the elevator with the door open. Note the signal strength and check if the phone works while the doors are open. Now close the doors of the elevator and call the phone inside. Note the signal strength and quality of the connection. Does the signal strength/connection quality change?
- The phone still worked when the doors were open. The signal strength went down to one bar while in the elevator and then went away. The call did not go through in the elevator.
4) Wrap your phone in foil and make a small hole in the aluminum so that you can see the signal strength. Slowly and completely wrap your phone in the foil and observe any resulting signal strength change. Describe what happens to the signal strength as the phone becomes entirely wrapped in the foil.
- When the phone was without the aluminum foil it had full bars of signals. When I started wrapping cellphone the signal strength went down. I completely wrapped the phone in aluminum foil and then made a hole to look at the signal strength. When I immediately made the hole, I saw the signal bars go from none to one.
5) Now try a radio. Tune it to an AM station. Does the station come in clearly? Why or why not?
- The radio came in fine when it wasn't wrapped with anything.
6) Take the radio outside. How does the sound quality compare inside versus outside?
- The radio sounded about the same outside and inside. It did seem to have a little bit less static outside, but it was not too much of a difference.
7) How does the sound quality compare just inside and just outside the doorway to the outside?
- I assume this question is asking how the sound was inside and outside the elevator.I was not able to test the radio inside an elevator because I did the experiment at home and did not have an elevator at home.
8) While outside, wrap the radio in the material that best shielded the signal in the first exploration. What happens when the radio is entirely surrounded by this material?
- When the radio was completely wrapped in the aluminum foil, there was no radio signal and all you could hear was the static.
9) What happens if you only partially wrap the radio in this material?
- Some of the radio signals went through, but it was very static.
10) Try placing a sheet of foil on the cell phone. Can it recieve a call?
- Yes, the when it was called, the call went through.
11) What if you make it a hat covering 5 sides?
- The call was completely blocked.
12) How about for the radio?
- You could only hear static.
13) Now make multiple slits or small holes in your foil and then completely wrap your phone in the mutilated foil. What effect does this have on your phone? Can you still receive calls?
- Yes. Since the phone is not completely wrapped in the aluminum foil, it does not completely block the signal from the cell phone.
14) Investigate the result of wrapping the radio in the mutilated foil.
- There was mostly static, but you could hear a little bit of the radio signals that came through the mutilated foil.
15) What can you conclude about how to shield a device completely from EM waves?
- If you want to completely shield a device from electromagnetic waves, it must be completely wrapped in the shielding material in order to make a Faraday's Cage that will block the electromagnetic waves.
16) Now based on what you’ve learned, will the hats below keep the aliens from reading the EM fields coming from your brain? Why or why not?
- If you make a pointy hat made out of aluminum foil, it will not prevent the aliens from reading the EM fields coming out of your brain because a simple hat will not completely surround your whole brain so the Faraday's Cage effect will only partially reflect the incident radiation coming from the hat-wearer.
17)In X-Men, Professor X can read people’s minds. Does Magneto’s helmet (pictured below) better
protect him from having his mind read by Professor X than the couch monkey’s
hats, pictured above? Why or why not? Is it possible that he is completely safe from having his
evil plans found out by Professor X?
- Magneto's helmet is much thicker than the aluminum foil that the "couch monkeys" were wearing. If Magneto's helmet completely surrounding his brain, it will be much more efficient than the tin foil hat because it is thicker, which means that it could block higher frequency waves, which is probably how Professor X reads minds (if this was not fiction). Since, Magneto's helmet doesn't completely shield his brain, his helmet is completely useless.
Conclusion:
This lab is way to simple to be given to a 4B or even a 2BG student. This lab doesn't really teach you much besides the fact that completely wrapping something in aluminum foil will block electromagnetic waves. It doesn't clearly explain how Faraday's Cage works, nor does it mention it, which is the reason why the EM waves are blocked. It is not a qualitative lab that explains scientifically why this occurs, it is simply an observational lab. I strongly wouldn't recommend this lab unless it is for elementary or middle school students.
