Today we learned that the angle of incidence = the angle of reflection. If you don’t remember what this means then look at the photos. It is important that when you are asked to draw a reflected light ray you:

1. use a ruler
2. include an arrow showing the direction the light is travelling
3. make sure that the angle that the light bounces off the mirror is the same as the angle that it hits the mirror.

We looked at a SATs question that involved applying this today. We also saw a periscope and how it uses two mirrors to reflect light. You could be asked to draw the light rays entering or leaving a periscope.

http://www.glenbrook.k12.il.us/gbssci/phys/Class/refln/u13l1c.html

radioactivity

Today we measured background radiation with a Geiger Muller tube and we also investigated just how penetrating alpha, beta and gamma radiation are. We found out that:

1. alpha is stopped by air and paper
2. beta is stopped by aluminium
3. gamma is stopped by lead

We did a question about an aluminium foil factory. This is a question that comes up year after year so make sure you understand it.

From metals

 We found out today thay when you burn metals they react with oxygen in the air to make metal oxides. Because we added oxygen to the metal it was heavier after we burned it.