Everyone is probably familiar with the white noise or snow that can appear on an analogue television screen. I know this comes from electronic noise and stray electromagnetic signals, but television signals encode colour information, so how come this random noise always shows up as white?

Jack Bishop, Redditch, Worcestershire, UK

Flowers co-evolved with their pollinators: that is why they find flowers attractive. This arrangement works to the benefit of both parties, so do humans get any similar benefits from liking flowers? The plants do, in that gardeners propagate them.

Come to think of it, are other mammals attracted to flowers?

Jim Simons, Cheltenham, Gloucestershire, UK

I found this leaf (pictured) in a park in Oslo a few weeks ago. What is the explanation for this pattern of green pigmentation?

Fredrik Størmer, Oslo, Norway

What gives chestnut mushrooms their brown colour? The colour can be wiped away, leaving what looks like a standard white mushroom.

Barry Strong, Manchester, UK

For my 18th birthday I received a silver bracelet, with what I believed were amethyst or similar stones set into it.

However, the purple stones appeared blue under the flourescent lighting in the biology labs, and under another type of light seemed clear white. Once under sunlight the stones again appeared their normal purple colour. There was no gradual fade of colour - moving from one light to a window yielded instant change - and under normal lightbulbs the stones also appeared purple, and the same with any light mixed with sunshine.

Is this to do with how the stones were cut, how they reflect the light, or is the stone itself responsible?

Thanks,

Eleanor

Christopher Smithson, Leicester, UK

One of my young chickens has just produced an unusually coloured egg (to the right of the photo). The egg on the left is more typical of the breed.

I know egg shell colour is variable, even in eggs laid by the same hen on different days, but how did one egg undergo such a sudden and distinct colour change?

Colin Booth, Durham, UK

Do we all perceive color the same way ? for example do we all see the same color green or is the word green or red or blue just names to tag how we perceive those color. If I switched eyes with someone he might see the grass the same way as I perceive the sky but still call it green even though for me it would be blue.

The same goes for colorblind people (those unfortunate to mix up colors) if they were brought up seeing the grass as we would see it red. He would say green to everything red if we were able to see through his eyes. It would rely on education then.

Do I make sense ?

In my office we fill out a time sheet each week, which has a yellow background and must be printed out on a laser printer.  I print mine in colour, but many colleagues print the sheet in black and white so the background colour comes out light grey.  They claim this is more environmentally friendly.  But I say there's no evidence that black ink has a higher environmental cost than yellow ink, so it makes no difference.  Who is right?