Why is laser beam visible in mid-air from a 6 watts laser, but light is not visible in mid-air from a 100 watt lightbulb?
Even football field lights dont look visible in mid-air. Why is a laser beam visible?
- Steve4PhysicsLv 71 month ago
All the laser’s energy is concentrated in a very small cross-sectional-area beam (a few millimetres in diameter). The light scattered out of the beam (which is what you see) is relatively bright compared to the background.
Light from conventional bulb (even with a focussing mirror) is more spread-out over a much larger area. So the light scattered out of the beam is relatively faint compared to the background.
It’s like comparing undiluted squash with squash diluted in water so it’s a million times weaker.
- 1 month ago
because it's a beam. Surround your 100watt bulb with a light shield and poke a small hole in it, you will see a beam of light exactly like a lasers, but a different colour.
- A.J.Lv 71 month ago
I live in Las Vegas. The Luxor Sky Beam is a 42.3 billion candela tunnel of light. 39 xenon lamps on a clear night, is visible from 275 miles away by aircraft at cruising altitude. The beam’s 39 lamps are each 7,000 watts, as 273 kilowatts total, but since 2008, typically only half are lit.
The laser is a focused beam of narrow frequency. The output is actually lumens, lux, or candela, rather than the electricity used and you can separately look up how they relate. Light is either reflected or absorbed and we see light as it passes through the cornea, and then moves into the lens, which bends the light, focusing it down to a point on the retina, at the back of the eye. The retina is covered in millions of light-sensitive receptors known as rods and cones. If not looking at the source of light, you see reflected light from particles.
Since the laser is focused to a small beam in tight frequency it only strikes particles in the air in its path. The 100 watt bulb is in a wide field reflected and absorbed in a smaller distance. You see the light reflected from particles.
- MorningfoxLv 71 month ago
You see the light beams because they reflect off dust particles in the air. The laser light looks a lot different from the background light coming from behind it. The broad-spectrum light from the light bulb doesn't stand out from the background.
If the background was dark, they would both be visible.
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- 1 month ago
Directed light photons.
- cmac'mLv 51 month ago
You see the 'light' from 100watt bulb, it's all around. But a LASER "light amplification by stimulated emission of radiation" is focused and amplified. You see the beam when it travels through particles.
- Jim MoorLv 71 month ago
It's an issue of contrast.