What happens to intensity of light from a bulb if distance from bulb is doubled? As a laser beam tra

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8.Electromagnetic waves

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What happens to the intensity of light from a bulb if the distance from the bulb is doubled? As a laser beam travels across the length of a room, its intensity essentially remains constant. What geometrical characteristic of $LASER$ beam is responsible for the constant intensity which is missing in the case of light from the bulb ?

Option A

Option B

Option C

Option D

Solution

Intensity of waves is inversely proportional to source of distance from source $\left(\because\right.$ I $\left.\propto \frac{1}{r^{2}}\right)$ when distance become double then intensity become $\frac{1}{4}^{\text {th }}$ value they do not spread hence here inten sity remains same.

Following geometric characteristics of LASER beam are responsible for constant intensity,

$(i)$ Unidirectional

$(ii)$ Monochromatic

$(iii)$ Coherent light

$(iv)$ Highly collimated

These characteristics are absent in case of bulb in given case.

Standard 12

Physics

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