Gonna Give Einstein A Run For His Money In My Physics Exam. Not.

This could be a long post, so I'm just gonna get on with it.

Radioactivity --

Alpha (a) -

• two neutrons, two protons (helium)
• big, heavy, slow moving
• don't penetrate very well (stops at paper and skin)
• strongly ionising
• bent by electric and magnetic fields
• used in smoke alarms (because it's not dangerous to humans on the outside)

Beta (B) -

• one electron
• quite fast and small
• penetrate moderately before colliding and ionising moderately
• stops at aluminium
• bent strongly by magnetic and a electric fields
• used for thickness control (paper and rollers)

Gamma (y) -

• a wave
• penetrates a long way
• stopped by lead
• weakly ionising (passes through instead of collides)
• used for power generation
• used for checking welds
• used to sterilise stuff in hospitals

Problems with radioactivity -

• can cause cancer
• can cause mutations
• can be used for terrorism
• no where safe to store waste radioactivity

Half life

• radioactivity decreases over time, but never reaches zero. Half life is the time it takes for half of the atoms to decay.
• eg - 1000 atoms > 100 atoms... 1000/2 = 500... 500/2 = 250... 250/2 = 62.5... 4 x 2 = 8 hours / 4 half lives

Background radiation -

• is naturally all around us (but is no danger to our health)
• comes from the air, our food, building materials, rocks under our feet, space (cosmic rays) and human activity (nuclear explosions and waste)
• proportions are - 51% radon and thoron gas, 14% rocks, 12% medical x-rays, 12% food, 10% cosmic rays, 1% nuclear industry
• measured in Becquerel (Bq)
• 1 Bq = one nucleus decay per second

That's everything I have on radiation. It's a hell of a lot, and I still have Distance, Speed, Acceleration, Velocity, Forces, Car Safety and Electricity to get through. By Thursday.

Argh, wish me luck.