Anyone ??
ALPHA: stopped by paper
BETA: goes through paper, stopped by thin metal (aluminium)
GAMMA: goes through paper and metal sheet. Stopped by thick lead or concrete.
Credit: Took it from gcse.com
EDIT: If the image is too small, click
here.
EDIT 2: In the exam you will have to draw a source on one side of the aluminium sheet and a count-meter on the other.