You are Here: Home >< Physics

Can some one help me with this watch

1. Can you see the period of the wave for each of those time bases? The period is one complete cycle of the wave, so is 4cm for the displayed wave. Use the time base to convert that to seconds.

Once you have the period of the wave in seconds, you can calculate its frequency. Frequency is defined as the number of cycles per second.

2. I don't understand
3. (Original post by 999sian)
I don't understand
Try this for a simple explanation:

http://www.bbc.co.uk/schools/gcsebit...elecrev6.shtml
4. It's three different signals being plotted at three different timebases... which coincidentally have produced plots that all look the same (which allows the examiner to draw one diagram instead of three)

so you've got to work out the first frequency (as shown in the posts above) then repeat for the other two. just pretend that you're looking at a fresh plot each time.
5. Still don't understand can someone tell me what to do ?
6. (Original post by 999sian)
Still don't understand can someone tell me what to do ?
The best thing you can do is to watch this excellent video.

Follow it carefully and you will learn exactly what the basic measurements on an oscilloscope are and it will show you exactly how to solve this question and any others you are likely to encounter.

Pay particular attention to:

Amplitude
Period
Frequency

and the relationship between the period and frequency. Make sure you learn what these are.
7. Yeah i get alll that but i still don't understand what the hell the question is asking. the video is don't explain anything useful. just tell me what to do
8. (Original post by 999sian)
Yeah i get alll that but i still don't understand what the hell the question is asking. the video is don't explain anything useful. just tell me what to do
It's asking for a frequency, the unit of frequency is Hz

frequency is 1/period

period is the amount of time between one peak and the next

time is on the horizontal axis

count the number of cm between 2 neighbouring peaks

in part a there are 5ms per cm

so what is the time between those neighbouring peaks? this is your period

calculate 1/period

write it down with the correct unit for frequency

part a done.

now repeat for the different amounts of time per cm as given in the question parts b and c
9. Holy **** someone actually explains something thank you very much. for part a i got 0.05Hz for the frequany. in part B and C the units are differnt so how do i convert it to the correct units
10. (Original post by 999sian)
Holy **** someone actually explains something thank you very much. for part a i got 0.05Hz for the frequany. in part B and C the units are differnt so how do i convert it to the correct units
0.05 Hz is not correct. Also, you learn nothing if we do your homework for you by telling you the answers (which is what you seem to be asking for)
11. What did i do wrong then. i don't understand
12. All wanted was an explanation like the person above said. don't just tell someone their wrong explain how to get the correct answer. i know it 50hz now because of unit conversions. My Physics teacher is complete **** and gives us work to do and does not bother to teach us it and expects us to just know it and if we go and ask for help he just tells us off.
13. (Original post by 999sian)
All wanted was an explanation like the person above said. don't just tell someone their wrong explain how to get the correct answer. i know it 50hz now because of unit conversions. My Physics teacher is complete **** and gives us work to do and does not bother to teach us it and expects us to just know it and if we go and ask for help he just tells us off.
So you've got it now for all 3 parts?
14. (Original post by 999sian)
Each Square is a cm. One whole cycle (or wavelength) has 4 squares.
i) if one square unit is 5ms, one cycle takes 20ms (because 5msx4=20ms). Frequency(f) = no. of cycles/second. In this case it's 1 cycle per 20ms (convert to standard units. 1000ms=1second therefore, 20ms=0.02s) so f=1/0.02s=50Hz.

Apply the same method to the following parts. Was that helpful in making you understand?? If you become clear with the basic concepts, you'll have no problem in applying the same principle to other questions.

Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: February 8, 2017
Today on TSR

Exam Jam 2018

Join thousands of students this half term

Solo - A Star Wars Story

Poll

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE