Wangene's+AM+Radio+Lab

=AM Radio= Date of Publication (Date of Most Recent Edits)


 * Participants**: Wangene H. Mike B. Trevor W.
 * Purpose**: The purpose of this lab is to explain what a resonant circuit is and how it functions in a radio.
 * 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**: In this experiment, we studied how inductors and capacitors function in radios. We calculated the values needed for the inductor and capacitor and set up the radio according to those values. The capacitor was made of two sheets of aluminum foil secured between the pages of a book. The inductor was made of copper wire wrapped around an expo marker. The inductor was wired to the capacitor in a square configuration, creating the bulk of the circuit. Attached to each side of the capacitor is the other part of the radio, the demodulator and the electric and audio listening device (the headphone). On the opposite end of the inductor-capacitor setup (the resonator), an antenna (battery) was attached to the inductor. We controlled the frequency of the radio by changing the inductor and capacitor.




 * Data**: Create a table (when appropriate) including all data collected or calculated during the lab. Be sure to include a heading for each column that includes the units of each measurement.

Calculations// || 900000 = 1/2pi * 1/(LC)^1/2 5654866.776 = 1/(LC)^1/22 (5654866.776)^1/2 = ((LC)^-1/2)-2) LC = 3.127E-14
 * Sample Calculations:**
 * //Resonator Design

L = (4piE-7 * 50^2 * .02835)/.08 = .0011134147

A = pi * .95^2 = 2.835 C = 2.80865E-11 (freq: 900 Hz) C = 1.16071939E-11 (freq: 1400 Hz) || We determined that the values for the inductor and capacitor that we calculated were correct. We made an inductor with 50 coils that had a length of .08 cm using an area we calculated. When we used the 1400 Hz frequency station, we heard a talk show station. We were also able to replicate the experiment on the 900 Hz frequency range. We discovered that the capacitor disrupted the radio signal, particularly when the capacitor contained larger sheets of aluminum foil, because it provided a resistance that was too high. We also discovered that the radio worked slightly better when connected to a stronger ground source-- such as wires strung over a taller height vs. the wire connected to the electrical outlet.
 * Results**: Describe the major result of the experiment and how you arrived at this result. Typically, this will refer back to the purpose. For example, if the purpose was to find the frequency of the inductor and capacitor in an AM radio, you would write:

The resonant circuit is the inductor-capacitor portion of the radio that receives the radio frequency. It does so by having a specific frequency at which it will receive vibrations as determined by the resistance of the circuit (related to Q factor) and the square root of the inverse of the inductor * capacitor. A resonant circuit contains a capacitor-inductor system that allows current to flow backwards and forwards. It is attached to an antennae (battery) which receives the signals being sent over the air & a ground source that ensures it is connected to a negative source. The demodulator portion of the radio has a diode that takes away the carrier wave, only allowing positive frequencies to be heard. The headphones allow the frequency to be heard by converting electrical signals to audio waves.
 * Lab Questions**:
 * What is a resonant circuit? What elements does it contain? How do those elements work together to amplify the carrier frequency?**

Our resonant circuit has a frequency of 1400 Hz and 900 Hz when its inductance is .0011134147 and the capacitance is 2.80865 x 10^-11. We know what its resonant frequency is because a statio can be heard.
 * Describe your particular resonant circuit & its elements. What is its resonant frequency & how do you know?**

Resonance is an effect that is nullified by too much resistance. The resonant frequency is the specific frequency at which the resonator can clearly read signals. When the resistance of the circuit it too high, it affects the capacitance, thus rendering the resonator less effective.
 * Address the effect of resistance on resonance:**


 * Conclusion**:
 * The radio first played the wrong station because AM radio signals weren't strong enough in our area, and the antennae we used had limited ability to pick up signals.
 * The experiment might have been improved if a more coiled capacitor was used or if the antennae could pick up signals better.