ANNOUNCEMENTS FOR STANDING WAVES ON A STRING LAB
(Updated August 26, 2007)
General Announcements : Uncertainty : Inclined Plane : Conservation of Mechanical Energy : Collisions - Conservation of Momentum : Conservation of Rotational Kinetic Energy : Simple Harmonic Motion : Velocity of Sound in Air : Standing Waves on a String
Important Announcements
1. Please check your lab grades on this web site. It is not unusual for errors to creep into the official records and it will soon be too late to correct them. If you spot a problem, first try contacting your TA to clear it up. The grades posted on the web do NOT yet include all of the penalties that may be assessed for issues such as arriving late to lab nor are they renormalized yet to correct for grading differences between the TA's.
2. If you missed a lab and wish to take a makeup lab, you must arrange that as soon as possible. Even if you previously requested a makeup lab, you should confirm this request now. Students may only do one makeup lab. These are offered from 8:30 AM - 11:30 on the first Reading Day before Final Exams (Monday, December 10th). The finished reports are due in by 6:00 PM of that same day. These labs will be supervised and graded by someone who may not be your regular TA.
There are four setups for Lab#7A and four for Lab #7B in each room. You will switch experiments 90 minutes into the period.
For Lab #7, there is no report and the worksheet should be completed during the lab period and handed in with the notebook copy. Simply hand the necessary material to your TA before you leave the lab and you are finished with physics lab for the semester. The worksheet for Labs 7A & 7B will be graded as a single entity, worth 30 points total.
Your TA will distribute a Lab Evaluation form that should also be handed in (placed in the envelope supplied for this purpose) before you leave the lab. These forms are for our internal use; they will be reviewed (after grades are in) as part of our regular efforts to improve the intro physics labs.
ANNOUNCEMENTS FOR STANDING WAVES ON A STRING LAB
The pictures below illustrate the steps in tying a slipknot. If there is an object inside a slipknot when you pull on the ends of the string, the knot will tighten around the object. It the knot is empty, you can remove it completely by pulling on the ends of the string.
Tie one end of the string, with a slipknot to the bar to the right of the string driver and then slip the string into the notch on the red bar shown below. Then cover the notch with tape to help keep it in place.
The electronics for this experiment are pictured below.
You may have either of the two types of function generators shown below. The power switch for the function generator on the right is located on the rear of the unit. Note that the frequency generated is the product of the "fine-tune" frequency knob labeled on the pictures and a "frequency multiplier." This multiplier is set by the button controls for the function generator on the left. It is set by the knob just to the right of the "fine-tune" frequency knob for the function generator on the right.
A good pattern with a node in the center and a wavelength almost as long as the string is shown below.
Note that the node near the driver should be a few cm away, the driver itself is always moving and so cannot be a true string node.
Note that if the Digital Multimeter is set to read frequency with maximum 20 kHz, it will display frequencies in units of kHz.
General : Uncertainty : Inclined Plane : Conservation of Mechanical Energy : Collisions - Conservation of Momentum : Conservation of Rotational Kinetic Energy : Simple Harmonic Motion : Velocity of Sound in Air : Standing Waves on a String