Ryan's+AM+Radio+Lab

=Raaa-di-OH= 3/3/10


 * Participants**: Ryan Payne
 * Purpose**: The purpose of this lab is to find a system with a resonant frequency that will pick up a near by AM radio signal.
 * Lab Documents**: Include a link to any documentation provided for the lab or any references used in writing the lab report.


 * Brief Description of Experiment**: Finding an AM radio station requires a resonant circuit that amplifies the carrier frequency. What we will be doing in this experiment will be creating a capacitor / inductor pair that will give a resonant frequency of 900kHz (900,000Hz) to pick up a strong local AM radio signal. Our design consisted of a capacitor made from a book with two sheets of aluminum foil, a inductor made form copper wire wraped around a watter bottle, and a headphone. We connected them all together to make an AM radio the signal we picked up was really weak and feighnt. However we were not sure if we ended up intercepting the correct station we wanted. We thought this was possibly due to the resistance in the wiring that might have thrown off our calculations.


 * Data**: Here are some pictures to explain the lab:



This picture shows somebody listening to Trever and Mikes radio, which was essentially the same as ours with some little changes.





Our Resonant circuit Sample Calculations: Describe or reproduce any calculations that are performed during the experiment (other than averaging). For example, if you use a distance and a time to calculate a speed, you should show:

Shown below are calculations that were initialy working. but somehow they decided to get all funky on me.

math 1 / 2\pi \sqrt{LC} math || C = ε0 A(m^2)/d(m) math || L = μ0 N^2A(m^2)/l(m) math ||
 * < Resonant Frequency ||= The resonant Frequency is the frequncy at which.... =
 * < Capacitance ||= math
 * < Inductance ||= math

These were our calculations that we did:

We calculated that our capacitance was two square sheets of aluminum 0.2m x 0.2m with a distance between them of about the depth of one sheet of paper (6.7 x 10^9m). Our inductor had a diameter of .09m wrapped five times. The length of the coil was .015m with an area of .00636m. Then we found the resonant frequency by using the equations (above) for L, C, and the resonant frequency. LC came to equal 3.12 x 10^14 and then plugging into the resonant frequency we determined a frequency of 607,479Hz (607kHz).

Our results are that we successfuly created an AM radio circuit that was indeed able to pick up a neer by radio signal. After struggling with minor details we were able to listen to what was on the radio station.
 * Results**:


 * Lab Questions**: Address one of the following:

--> Effect of resistance on resonance

--> Diodes and Demodulation

The term diode is used in electronics. It is a two-terminal electrical component that is a conductor that conducts current in only one direction. The most common diode today is called a semiconductor diode. another diode is called a vacuum tube diode, which is not used as often anymore. The use of diodes are to convert an alternating current (like our AC current in our radio circuit) into direct current. Also the diode extracts modulation from radio signals. This is called demodulation. Demodulation is used to get the information from the original modulated carrier wave. This is helpful in our circuit so we can hear what the radio station is playing.

--> Headphones and Electric to Audio Conversion

Headphones are small loudspeakers that can connect to a source of audio outout like a radio, CD player, ipod or another of the sort. We used our headphone in our AM radio circuit so that we could hear the electrical waves that we were recieving from a nearby radio station. The loudspeakers inside the headphones are the devices that did the converting of electrical waves to audio. To do this the speaker moves in accordance to the variations of signal and causes the sound to move through a medium like air.

--> Antennas + Conversion of EM Waves to Currents

Antennas transmit or recieve electromagnetic waves. They are used with radios mostly. They are used to communicate over long distances. Antennas are made up of one or more conductors. An alternating current is created in the conductors by applying a voltage causing tha anntenna to make an electromagnetic field. In a recieving antenna (like we used) induces alternating current in the electromagnetic field.


 * Conclusion:** We successfully created a valid circuit that recieved an AM radio signal. If we were to do it again it would go a lot quicker and easier. It took a while to find the correct setup that produced sound but we finally did. One of our biggest problems was getting the capacitor to work correctly. We noticed at first that our capacitor worked without connecting to both sides to complete the circuit. Also the distance between aluminum plates in the capacitor was not the same as we calculated. We learned that these things could have been due to the natural resistance in the wire that we used. We did not account for this resistance in calculations.