1 / 13

Minilab 1 Standing Waves

Minilab 1 Standing Waves. Page 1. PURPOSE. Today, we will observe standing waves on a string in order to learn and verify how the formation of standing waves depend on: Excitation Frequency Tension of the string Linear mass density of the string. Page 2. THEORY.

oded
Télécharger la présentation

Minilab 1 Standing Waves

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Minilab 1Standing Waves Page 1 Department of Physics & Astronomy

  2. PURPOSE Today, we will observe standing waves on a string in order to learn and verify how the formation of standing waves depend on: Excitation Frequency Tension of the string Linear mass density of the string Page 2 Department of Physics & Astronomy

  3. THEORY When a wave moves along a string, we say the wave is propagating along the string, as shown. The linear mass density is related using: The density and the tension of the string (T) affect the velocity that it propagates at: v Page 3 Department of Physics & Astronomy

  4. Note that waves reflections depend on how the string is attached at one end. End of string is fixed, the wave gets inverted End of string is loose, the wave is not inverted Theory Page 4 Department of Physics & Astronomy

  5. We use the term superimposed to mean two waves that are overlapping. Below, these two waves are travelling in opposite directions. Moving to right Moving to left theory The sum of the two waves (“superposition”) Anti-Nodes Nodes Page 5 Department of Physics & Astronomy

  6. If the length remains unchanged, standing waves only occur at specific frequencies. In our case, we have strings with nodes at both ends, which produces the following: theory l l/2 3l/2 Page 6 Department of Physics & Astronomy

  7. The two nodes are here equipment Mechanical Wave Driver creates waves (Frequency and Amplitude controlled by Capstone Software) Mass creates tension in string: T = mg Page 7 Department of Physics & Astronomy

  8. Experimental Determination of Speed of Wave • The velocity of the wave can be calculated as follows • V = f l (or f = v/ l) • (read off frequency in Capstone Software, measure l when you see a standing wave pattern). • Start from low frequency and observe several different standing waves (different f and l). • Plot f versus 1/ l The slope of this graph equals v. • Repeat the procedure using a different tension in the string (use a different mass at the end of the string). V should be different because it depends on the tension T. procedure Page 8 Department of Physics & Astronomy

  9. Once you have collected your data, you will need to plot f versus 1/λin Excel. The slope of your graph is equal to v. If you are still having struggles with plotting in Excel, please refer to the Excel Tutorial online, or make sure your lab partner can explain it to you! procedure Page 9 Department of Physics & Astronomy

  10. Theoretical Determination of the Speed of a Wave As we saw above, the theoretical speed is: To find , you will first need to find with a ruler and the scale. Also note that 2 m procedure Page 10 Department of Physics & Astronomy

  11. You then need to get lunstretched with your ruler by taking the string off the pulley system • To find mstretched, we need the following equation: • mstretched = munstretched * lunstretched • When we plug this intomstretched , we get • Please correct this last equation in your lab manual on page 14! It is incorrectly printed there. procedure Page 11 Department of Physics & Astronomy

  12. Finally, to compare the theoretical and measured velocities, use percent difference: procedure Page 12 Department of Physics & Astronomy

  13. Final hints Homework Policies You must do your homework BEFORE CLASS, and everyone must turn in their own work. Lab Report Policies Submit one lab report per group. Groups should generally consist of two people. Make sure both members of the group write their name on the lab report! Page 14 Department of Physics & Astronomy

More Related