Question

The light intensity 3 m from a lamp that emits 25 w of light energy will be

Answer 1

the light intensity 3m from a lamp then it's energy will be 400k

Answer 2

Given that,

Power emitted by a lamp, P = 25 W

Distance, r = 3 m

To find,

The intensity of light energy.

Solution,

Intensity is given by power per unit its area. It is given by :

$I=\dfrac{P}{A}$

A is area,

$A=4\pi r^2\\\\A=4\pi \times (3)^2\\A=113.09\ m^2$

Intensity is given by :

$I=\dfrac{25\ W}{113.09\ m^2}\\\\I=0.221\ W/m^2$

So, the light intensity of light energy will be $0.221\ W/m^2$.

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