Simple electric device Essay

Physics lab BY Alleluia Measuring Time Date Due: 2013. 09. 23 Lily Lie Name: Class: A Teacher: Mrs. Slater Purpose: To determine the period and the frequency of a ticker timer. Materials/Apparatus: One ticker timer One 1. 5+ meter tape One stop-watch Theory: One carbon paper disc One test tape The recording timer is a device that helps you study motion, it is a simple electric device plugged into mains power, with a stylus that vibrates up and down. The stylus hits a tape that can be drawn through leads, and presses it onto the carbon disc below.

This leaves a dot on the tape for every hit. The power source ensures that the vibration of the stylus will be regular. The period(T) of the timer it takes for the stylus to move all the way down and then up-one complete cycle. The frequency(f) of the timer is how many times the stylus goes through a cycle in a second. So the frequency. We will calculate the frequency using formula Frequency(f)=number of dots/ time, and then calculate the period using formula Period(T)= per unit time/ frequency. Procedure: 1 . Follow instructions and assemble the apparatus. . Put a carbon paper disc which is carbon-side-up on the fix shaft between the attest. 2. Place a short strip of timer tape in the recording timer over the paper disc. 3. Make sure the tape is threaded through the gates and is free of snags. 4. Turn the timer on and pull the strip through the gates. 5. Make sure you are getting dots on the underside of the tape. 6. Use the test tape to decide on the best speed to pull the tape, so that the dots are easy to read. 7. Place a +1. 5 meter piece of tape in the timer. 8.

Pull the tape through a gentle, constant motion with one hand. 9. As you pull, operate the stop-watch with the other hand. The time should be close to 3 seconds. 0. Turn the ticker timer off. 11. Remove the tape and mark on it the exact time it took to run the tape. 12. Count the dots on the tape and calculate the frequency and the period of timer. 13. Re-do the above if the results are not satisfying. 14. Repeat the above for all members of the group. 15. Tabulate everyone’s results and compute all the results. 16. Enter all data in the table. 17.

The paper tape is not straight when pulling so it may resulted in inaccurate number of dots. 3. During the experiment on two occasions the disc would either not imprint anything on to the ticker tape paper if the needle was too high or come off during the experiment as it turns. This resulted in trails having to be repeated and the waste of lab materials to retrieve accurate data. 4. The time we release and pull the tape and the operation of the stop-watch were done by two hands. This created the possibility for the tape to be released slightly before or after the timer was activated. . The ideal time is 3 seconds. However, it is next to impossible to be that exact. Such a synchronization problem can change the records of the number of dots but may not seem drastic since we are focused on the frequency and the period of the ticker timer. Percentage Error: argental error= [experiment value – accepted value/ x 100 accepted value error in opened XIII Critical Analysis: This lab shows how we can further get to know a ticker timer by applying the knowledge of frequency and period.

Through the lab, I knew that frequency is the number of occurrences of a repeating event per unit time and the period in seconds, meaning the number of seconds per cycle. The lab worked out well in our group with a percentage of error of less than 2% but I still found some possible improvements that can make the results more accurate: 1. We could try pulling the tape before tarring the ticker timer and the stop watch to eliminate the miscounting of the numbers of dots caused by blotching of dots at the beginning of the tape. 2.

Invest in a digital photo gate to eliminate the error caused by stopping and starting the stop watch effectively. 3. We can get a more accurate results by pulling a longer tape for as so that some inevitable errors can be minimized. 4. Pull the tape along the edge of the table to have a better result of dots on the tape. Every experiment has errors, but that doesn’t mean we are certain to make mistakes, we should be aware of that something we cannot control should lead to errors, yet we need to endeavor to minimize the errors by some methods. Extension Questions: 1 . Why is it important not to pull the tape too quickly?

Firstly, once the tape is run out before 3 seconds, we surely need to re-do the lab, thus it would be a waste of time (shorten time for getting a more perfect result) and experiment materials. Secondly, if the dots are recorded entirely, you would find that the distance between two dots are long and harder for us to count the number of the dots. Thirdly, because of the high pulling speed, the spots on the tape maybe light- Loren, it is more likely for us to ignore some of the dots, which will certainly lead to human errors. 2. Why is it also important not to pull the tape too slowly?

Pulling the tape too slowly would make the distance between two dots too short, in extreme cases, the dots may coincide, therefore it is harder for us to get exact number of the dots which furthermore will affect the accuracy of the whole experiment. 3. Does is matter whether the dots are unevenly spaced along the tape? What would that indicate? It does not matter. Since what we need is only the umber of the dots in order to calculate the frequency and the period of the ticker timer, the formula we used would average out the number of the unevenly-spaced dots during per time intervals.

Therefore, the distance between any two of them doesn’t affect the results. However, it indicates that we didn’t pull the tape through a constant motion. 4. Would your results be more accurate if you had drawn a longer piece of tape for 5 seconds? Explain. Synchronization problem as we cannot switch on the ticker timer the same time we start the stop watch, and we cannot switch off the ticker timer the same time we stop he stop watch are inevitable. Thus however long the experiment takes, there should be some errors.

Whereas, if the period and frequency are calculated by a larger number of dots and a longer experiment time, the results will be more accurate and minimize the error. In order to achieve this, we could, for example, pull a mm+ piece of tape for as. Relevant research: It is apparent that frequency is equal to the reciprocal of the period f =I/T, so it is an inverse relationship and it is a measure of the periodicity of the function. If the number of counts is not very large, it is more accurate to measure the time interval or a predetermined number of occurrences, rather than the number of occurrences within a specified time.