Question

A mass of lead is embedded in a block of aluminium (2 mm thick). Radiations from a radioactive source incident on the side of the block produces a shadow on a fluorescent screen placed beyond the block. The shadow of the block of aluminium is fainter than the shadow of lead. This difference is because

• A. No radiations can penetrate through Aluminum but γ – radiations can penetrate through lead
• B. No radiations can penetrate through lead but γ – radiations can penetrate through Aluminum
• C. All radiations can penetrate through lead but γ – radiations can penetrate through Aluminum
• D. All radiations can penetrate through Aluminum but γ – radiations can penetrate through lead

Answer 1

The correct option is B

No radiations can penetrate through lead but γ – radiations can penetrate through Aluminum

γ - radiations given out from a radioactive source are able to pass through 2 mm aluminium block, while β-particles and α - particles are unable to penetrate through it. However none of the radiations can penetrate through lead. So, a fainter shadow of the block of aluminium is produced as compared to that of Lead.