A mass of lead is embedded in a block of wood.  Radiations from a radioactive source incident on the side of block produce a shadow on a fluorescent screen placed beyond the block.  The shadow of wood is faint, but the shadow of lead is dark.  Give resaon for this difference.

If the block of wood is replaced by a block of aluminium, will there by any change in the shadow?

Asked by Topperlearning User | 21st May, 2014, 04:18: PM

Expert Answer:

The shadow of wood is faint because only the -radiations are stopped by wood (since -radiations are least penetrating).  The shadow of lead is dark because -radiations are also stopped by lead.

If wood is replaced by aluminium (or any other light metal), the shadow of aluminium block will remain faint because aluminium will not stop the -radiations.

Answered by  | 21st May, 2014, 06:18: PM