mrmackenzie

AH investigation report guidelines

by

You should all be well underway with the writing phase of your investigation now.  I have attached some guidance from the SQA that is designed to help you with this.  Check pages 5-9 of the attached pdf document for detailed information on what is required of you in the final report.  Note the word limits and detailed specification of what the marker will be looking for in each section.

Remember that detailed feedback from me will only be possible if I receive your draft report by 3.30pm on Friday.  The deadline for submission is the end of the first week back at school after the Easter holiday.

eBook Download

interference simulations

by

We’ve been looking at interference recently.  I found two nice simulations that you might want to try running at home to confirm your understanding of things like;

  • relationship between fringe spacing in the pattern & wavelength
  • location of the 0, 1st, 2nd order fringes
  • what happens when the screen is moved towards/away from the 2 slits/sources

The first simulation is based on the interference of sound waves and is similar to the experiment we set up last week in class.  Click on the image below to start the simulation, you will need Java for this to work.  Make sure you choose the two source interference tab as shown in the picture.

The second simulation can be run as sound, light or water waves.  I selected the light option for this screenshot.  Click on it to run the simulation.  You are free to run 2 sources or one source with a double slit barrier and adjust the amplitude and wavelength.

The view screen option is nice as it shows what the fringes would look like.  You can also display a plot of light intensity (irradiance).

S3 How a TV works

by

one less tv by Kevin Steele
Attribution-NonCommercial License

I showed you a handy site that explains nicely how all the parts of a TV set come together to produce a “moving image” on your screen. You can visit the site yourself by clicking here.

The site covers

  • pixels
  • brightness control
  • moving the spot around the screen to produce an image
  • displaying many separate images per second

how a picture tube works

by

Today we looked at the way in which a tv set produces a picture.  We used the Maltese cross tube to produce the effect shown in this photograph.

  • Can you explain why there are two shadows of the Maltese cross on the screen?
  • What evidence can you remember from the lesson to justify your explanation?

Then we moved on to the Perrin tube.  This allowed us to scan the electron beam across the painted end of the tube using the magnetic field of two Helmholtz coils.  Here is the video clip we recorded at the time.

raster scan from mr mackenzie on Vimeo.

  • Why is the scanning pattern shown in this video different from the scan used in a tv set?
Podcast Video [ 0:12 ] Download (352)

Did you think quantum tunnelling was just a useless theory?

by

There’s a nice item on quantum tunnelling on the BBC News site.

image courtesy of Peratech

Scientists at Peratech have developed “spikey” particles for use in the touchscreen of  smartphones. The breakthrough is that the quantum tunneling effect means that the screen is pressure sensitive.

I found this video on quantum tunneling on youtube.

Centripetal acceleration and Isaac Newton

by

It’s a few months since  we looked at centripetal acceleration in class but I thought I would share this article I found.  I wonder how many people would dare to “co-write” a physics paper with Isaac Newton?  The article is worth a read and I have attached a download link below.

While we’re talking about centripetal acceleration, Rhett Allain’s blog post that led me to the article is also very interesting.

eBook Download