BBC - Rough Science - Message Board



The winner of the challenge to make a camera is Mike Welch, who was the nearest to getting the answer right. The runner-up is Mr (or Ms) "Binraker", who was heading in the right direction and he or she might have been able to build on what they had written down once they had tried it out.

Weel done to them both. They'll both receive Open University Science T-shirts. Here are their solutions.

Mike Welch
You have selected the following objects: silver jewellery, copper & zinc coins, sea shells, sheet of scrap metal, baked bean tin, seaweed, wire, sand, broken bottle.

Pee in glass vessel. Attach pc wire to Cu [copper] coin, & another to Zn [zinc]coin. Put 2 coins (not wire) in wee battery. Put sheet scrap metal in 2nd glass vessel with other end of one wire att'd. Fill 2nd glass vessel with clean sea H2O (Taste H2O to ensure salty) with which mix 50% of iodine solution made from crushed seaweed in minimum of H2O, filtered thro' sand in neck end of broken bottle. Suspend silver jewellery on other end of other pc wire in sea H2O. Check Ag (silver)jewellery fizzes & Ag [silver] deposited on scrap metal. If not reverse polarity (swap wires). If Ag [silver]deposit on scrap metal "fluffy", dilute sea H2O with fresh drinking H2O & rpt till firm dep. Ag [silver]on plate. Clean up all parts, make dark box with wood & nails, covered in darkest poss. cloth; set-up silver iodide plate making lab as above inside dark box, making final connections at night, in darkest room available. Before light, disconnect silver Iodide coated plate & place in base of a flat bottomed pan. Place clean b-b tin on top, (other end covered in paper with pin hole in). Fill space round b-b tin with dry sand to support. Fashion wood cover leaving pin-hole clear. In bright light expose req'd picture 1 min. Dismantle in dark. Develop in sol'n crushed filtered sea shells in urine in dark for 1-2 hrs. Dry plate & look at photo! Best of luck, Mike Welch

Mr (or Ms) Binraker
You have selected the following objects: sheet of scrap metal, baked bean tin, broken bottle, seaweed, silver jewellery
Attach the bottom of the bottle to the end of the baked bean can with either string or dried sea weed. Cut the scrap metal, with a hammer and screwdriver, if nothing else, to the shape of the end of the can. With a file make silver filings from the jewellery and mix with sea water,leave in a darkened room until lots of silver compounds have formed, spread in the scrap metal and fit to the end of the tin, use a shell as a lens cap and to take a photo just point in the direction of the thing to be photographed and leave the shell off for a few minutes.