S4 – changing state

We finished the Energy Matters topic last week.  Here are some notes with worked examples to show how we calculate the heat energy required to change the state of matter.  Values of Lf and Lv are provided inside the front cover of a question paper.

We’ll finish off the course by looking at Space Physics.

booklets for all standard grade physics units

I’ve been asked to post a link to all of the booklets so that people have access to something like the energy booklet as they revise using electricity and electronics.  I’ve added these to the standard grade page now.  Look for a link called whole unit notes in each section.

For those of you who have yet to download a copy of the SQA Physics booklet, get yours here.

nuclear fission

We looked at generating electricity using hydroelectric and nuclear power stations today.  Click on this image of a hydroelectric station to see how they work.

Nuclear fission occurs when a large nucleus splits into 2 or more smaller nuclei.  In nuclear reactors, splitting of the large uranium nucleus is achieved by adding a neutron to make the large nucleus unstable.


Animation showing fission of U-235 by Stephan-Xp

The animation above shows a (blue) neutron destabilising a large (red) uranium nucleus to cause fission. When the 2 smaller nuclei (also red) are released, notice that three (blue) neutrons are produced as part of the fission process.  These new neutrons can proceed to interact with other uranium nuclei and cause further fission to occur.  If the reaction continues to take place, we have a chain reaction.

This youtube video uses mousetraps and table tennis balls to demonstrate a chain reaction.  Notice how the reaction keeps going after the first ball is added and only stops when all the mousetraps have sprung.

Generating Electricity

Someone asked me about the animation I used last week when we were looking at the generation of electricity. The file is a java applet, this means you will need to install java on your computer if you do not have it already. You can view the animation here.  If it won’t run for you, try downloading the free java software.