Science Buddies: "Ask an Expert"

Hello sir/madam,

i have finished the experiment to determine the track spacing in a cd and dvd (https://www.sciencebuddies.org/mentorin ... ?from=Home). My values for the 2 cd's i used are:-806.7 and -838.26; and for the 2 dvd's are: -1335.93 and +105.51. I am not able to explain the reason behind the negative sign and the huge difference between the cd and the dvd. Kindly help me out. I have put in a lot of effort to find the readings and am feeling really lost right now. Thank you.

Kujan

Hi,

Can you post your raw data here (the measured angles you used in your calculation for the two CDs and two DVDs) ? I want to do a check with your numbers. Maybe after that I can shed more light on your questions.

Thanks.

hello Mr.Ghariman,

really appreceate you reply. My data is in an excel file. So if you give me an email id. I can send it to you as an attachment, along with my primary data (the pictures). Thanks again.

Kujan

Hi again,

Well I don't want to post my email address here (as I accidentally did yesterday in another posting) because I may start getting email-spam.

Could you please do me a favour and try to write it out here in the forum ?

Sounds good to you ? And when you write your data please make sure to label them appropriately (with the same naming as in the formula).

I hope then I will be able to help you a bit more.

hello Mr. Ghariman,

again i sincerly appreciate your effort to help me out. I do not have much time as my board exams are coming up. I am really running short of time. My error was a last minute discovery, so am really in a fix right now. I would be exteremely greatful for you help. Thank you.

Kujan

Dear Kujan,

I noticed that you posted your personal email on our discussion board. Science Buddies asks that both students and Experts refrain from posting their personal email addresses on the forum boards for your own protection.

Please email your Excel file to [email protected] and we will forward the email to ghariman so he can review your work.

I have removed your email from the board.

Thank you for your cooperation.

Regards,
Melissa G.
Program Administrator

Hi,

I got the data from Kujan via Admin.
I am looking at it now.
I will email it back to Kujan via Admin soon (as I also have my real-work to do here at work).

Hi Kujan,

Just sent a reply to you via Admin (with some documents attached).
Hope you receive it soon from them.

Thanks a billion Mr.Ghariman,

truly appreciate your help. Will get back to you as soon as i get the mail. Thank you.

Kujan

Hi again,

got your files...made the necessary corrections. I still have a doubt about the positive angles +1 and +2...i will email you my primary data in a zip folder...if its not too much trouble for you...kindly go through it and check whether it corelates with my data. Thank you.

Kujan

Hi again,

Here is a website with measured data for CD vs. DVD:
http://electronics.howstuffworks.com/dvd3.htm

Your final data should be approximately in this region for both CD and DVD. If they are not then you may have done some measurement errors.

Did you get the email from Admin yet ?

I got the email...thanks a lot...implemented corrections suggested...my only problem is locating the angles +1 and +2. Thats my only doubt. Thank you.

Kujan

P.s.I have sent you the pictures of one cd and a dvd. Kindly go through it and tell me what you think.Thank you.

Hi,

I sent a reply once again via Admin (contains 2 files). I think you managed to get to the same conclusion by yourself. Good work !

Good luck with the remainder of your project.

kujan wrote:I got the email...thanks a lot...implemented corrections suggested...my only problem is locating the angles +1 and +2. Thats my only doubt. Thank you.

Kujan

P.s.I have sent you the pictures of one cd and a dvd. Kindly go through it and tell me what you think.Thank you.

Hi,

In my two files (that I just sent via Admin again) you will see what your problem was (hint: m = 0 does not count as a data point). Let me know once you receive the new files and understand what is going on.

The two files are called "Kujan2.doc", the other is called "Physics Proj Version GH final.xls".

Glad to be able to help.

ghariman wrote:Hi,

I sent a reply once again via Admin (contains 2 files). I think you managed to get to the same conclusion by yourself. Good work !

Good luck with the remainder of your project.

kujan wrote:I got the email...thanks a lot...implemented corrections suggested...my only problem is locating the angles +1 and +2. Thats my only doubt. Thank you.

Kujan

P.s.I have sent you the pictures of one cd and a dvd. Kindly go through it and tell me what you think.Thank you.

i have not yet recieved the e-mail. Anyways, ill check it up tommorow morning..(its 2.24 in the morning here!)...Thanks a lot for you help Mr. Ghariman. Will get back to you asap. Thank you.

Kujan

Oh my. You must be located in Asia somewhere (guess => Asia SubContinent) ?

This is great. I thought I was only helping American students !!!
I myself am located in America but I went to HS in Indonesia.

The Admin just emailed me. She said she forwarded the documents to you just now.

Okay then. Good luck with the rest of your project.

kujan wrote:i have not yet recieved the e-mail. Anyways, ill check it up tommorow morning..(its 2.24 in the morning here!)...Thanks a lot for you help Mr. Ghariman. Will get back to you asap. Thank you.

Kujan

WOW...Im speechless...really dunno how to thank you for your help Mr.Ghariman. You dont even know me but uve helped me out so much...really dunno how to thank you. I owe you big time!

I went through the data...and its perfect...but i am unsure about how you made the changes (like the black patches). I am a novice at using the excel sheet. It was only two days back that i figured out how to key-in the formula. One last favour. Ill send you the remaing photos (for the other cd and dvd)...could you kindly fill in the changes for them too...hope its not too much trouble for you...already feeling kinda guilty abt takin up ur time...ill send it through Mrs.Melissa (in zip format). Thank you.

Yours sincerely,
Kujan

Hi,

I am pretty sure that you will do the same later in your life as others have helped me in the same way when I was a student.

Okay I sent a final EXCEL sheet with the data. Please try to understand first what is going on and then try to modify your own table following this understanding (as oppose to cut-and-paste from my tables).

Have fun !

kujan wrote:WOW...Im speechless...really dunno how to thank you for your help Mr.Ghariman. You dont even know me but uve helped me out so much...really dunno how to thank you. I owe you big time!

I went through the data...and its perfect...but i am unsure about how you made the changes (like the black patches). I am a novice at using the excel sheet. It was only two days back that i figured out how to key-in the formula. One last favour. Ill send you the remaing photos (for the other cd and dvd)...could you kindly fill in the changes for them too...hope its not too much trouble for you...already feeling kinda guilty abt takin up ur time...ill send it through Mrs.Melissa (in zip format). Thank you.

Yours sincerely,
Kujan