Effect of combining two source of light

[mohammadyou]

I wonder to know what would happen when we use two flashlight in a same direction. by doing so, do we extend the range of light?
if so, does it mean if the lights cross each other in a point perpendicularly the range that the light can traverse is going to reduce ?
I have been said that if we create a hole on a surface and put it in front of a light source, the beam that we created going further? if is it true What is the reason?
Tnx

 

[NascentOxygen]

I wonder to know what would happen when we use two flashlight in a same direction. by doing so, do we extend the range of light?
if so, does it mean if the lights cross each other in a point perpendicularly the range that the light can traverse is going to reduce ?
I have been said that if we create a hole on a surface and put it in front of a light source, the beam that we created going further? if is it true What is the reason?
Tnx

Hi mohammadyou, welcome to the Physics Forums.

You could say that a pair of flashlights will extend the useful range.

Light beams can cross and they'll always emerge undiminished.

I guess a piece of reflective material, with a hole, placed over a flashlight could give a slightly stronger beam, but only slightly. You probably wouldn't notice it without instrumentation. Why do you think the beam might be a little bit brighter?

 

[mohammadyou]

You could say that a pair of flashlights will extend the useful range.
Light beams can cross and they'll always emerge undiminished.

Thanks NascentOxygen,
Which kind of rule takes place that useful range with extend ? (thought Physics is not my field )

Why do you think the beam might be a little bit brighter?

I do agree with you, the power that added to beam is not too much but
some people use this trick in a sender and receiver infrared to extend their range !
and I consider this power negligible

 

[NascentOxygen]

If you double the number of sources, you are doubling the illuminating power. For the same intensity, the range will extend by a factor of √2, by this reckoning. Intensity follows an inverse-square law. http://www.portraitlighting.net/inversesquare_law.htm