What happens to t

The intensity of the light from the point source is given by,

Where,

r= Distance from the source

Now if the distance id doubled the intensity becomes one fourth times the original value.

For laser source the beam does not spread, so the intensity remains the same.

The characteristic of laser which causes the constant intensity and missing in the bulb are as follows,

 Monochromaticity

 Unidirectionality

 Coherent nature of light

 Highly collimated beam