What happens when red light shines on a red ball? It continues to reflect the red light, and so it is still red — but a white ball would also look red in red light, because it reflects all colors. If instead we shine blue light on a red ball, it will look dark, because it does not reflect blue light.

A red flag or any other red object will not be seen in red light. Any object appears coloured because it reflects the particular colour from the light that falls on it. A red object reflects only red colour.

An ideal red filter transmits only red light and absorbs all other colors. In this ideal case, a picture containing red, green, and blue would appear red and black when viewed through a red filter. A red filter blocks green light and blue light: Only red light can get through to your eyes.

black

For example the fruits which are red in colour like strawberries, tomatoes are rich in antioxidants and vitamins which are very healthy and milk, egg which are white colour are also healthy too. Deficiency of any vitamins may lead to health disorders. So if red becomes white balance may not be maintained.

When light hits a surface, some of it is absorbed and some of it is reflected. For example, a green object appears black in any other light than green (or white which contains green) because there is no green light shining on it to reflect into your eyes.

If a green and a red filter are placed together, what colours would you expect to be transmitted? (Answer – no colour will be transmitted, it will appear black. This is because a pure red filter only allows through red light and a pure green filter only allows through green light.

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Answer: they’ll be black, because green absorbs red.

Any color which reflects red will appear “white”, i.e. white, red, orange, yellow. Any color which absorbs red will appear “black”, i.e. green, blue, black. Colors that reflect some red appear gray, i.e. purples and some browns.

A Green object will ABSORB its complement (Magenta = Red + Blue). So, since Red light is ABSORBED by the Green pigmented object, NO LIGHT reflects back to your eyes, thus you “see” black.

This means that a yellow object will appear red under red light, and green under green light. Yellow does not contain blue, so it will appear black under blue light. White objects reflect all light, so will appear to be the colour of the light on them.

Seeing green happens when light excites the green cones more than the red cones. Seeing red happens when only the red cones are excited by high-wavelength light. Here’s where it gets interesting. Seeing yellow is what happens when BOTH the green AND red cones are highly excited near their peak sensitivity.

To the human eye, a green laser will appear four times as bright as a red laser at the same power output based on the human eyes’ light sensitivity. In ambient light conditions, our ability to see visible light peaks at approximately 555 nanometers (nm) and drops significantly within +/- 50nm.

Ask any worker, and he’d tell you that green laser levels are more expensive than their red counterparts. On average, a green beam laser level costs at least 20% to 25% more than its red counterpart. That’s because, the parts behind green levels – which makes their laser more powerful – doesn’t come cheap.

Green is more easily perceived by the eye and the beam is visible along its path. But green lasers are also more dangerous. Green is more easily absorbed by the retina than red, so it requires less exposure to cause damage.

While a green beam appears brighter to the human eye and often produces a crisper point or line, it is also more expensive and consumes more battery power. As there is no difference in accuracy between our red and green laser levels, the key differentiators are price, brightness, visibility range, and battery life.

Improperly used laser devices are potentially dangerous. Effects can range from mild skin burns to irreversible injury to the skin and eye. The biological damage caused by lasers is produced through thermal, acoustical and photochemical processes.

Lasers of even a fraction of a watt in power can produce immediate, permanent vision loss under certain conditions, making such lasers potential non-lethal but incapacitating weapons.

Although laser and IPL technology has not been known to cause skin cancer, this does not mean that laser and IPL therapies are without long-term risks.

The typical red laser pointer is about 5 milliwatts, and a good one has a tight enough beam to actually hit the Moon—though it’d be spread out over a large fraction of the surface when it got there. The atmosphere would distort the beam a bit, and absorb some of it, but most of the light would make it.