piteraufqvw

2023-02-18

The intensity of light produced by a light source varies inversely as the square of the distance from the source. If the intensity of light produced 3 feet from a light source is 750 foot-candles, find the intensity of light produced 5 feet from the same source. [4 MARKS]

kanadianugh93

Beginner2023-02-19Added 2 answers

Concept: 1 Mark

Application: 3 Marks

$\begin{array}{|cc|}\hline \text{Intensivity of light in foot candles}& \text{Distance from the source}\\ 750& 3\\ y& 5\\ \hline\end{array}$

$750\mathrm{\infty}\frac{1}{{3}^{2}}$

$750=\frac{K}{9}$

K=750×9

$y\mathrm{\infty}\frac{1}{{5}^{2}}$

$y=\frac{K}{25}$

$y=\frac{750\times 9}{25}$

y=270 foot candles

Application: 3 Marks

$\begin{array}{|cc|}\hline \text{Intensivity of light in foot candles}& \text{Distance from the source}\\ 750& 3\\ y& 5\\ \hline\end{array}$

$750\mathrm{\infty}\frac{1}{{3}^{2}}$

$750=\frac{K}{9}$

K=750×9

$y\mathrm{\infty}\frac{1}{{5}^{2}}$

$y=\frac{K}{25}$

$y=\frac{750\times 9}{25}$

y=270 foot candles