Question

(2 points) A pair of students measure the intensity of light from a desklamp in Sec. 4.5 of the experiment. When the detector is 25 cm from the lamp, the signal measured by the detector is 0.74 V. How large a signal (in V) do the students expect when the detector is 45 cm away?

Answer 1

Answer:

Intensity at 45 cm will be 0.2283 volt

Explanation:

We have given that intensity of signal measured by the detector is 0.74 volt at a distance of 25 cm

We know that intensity of signal is given by $I=\frac{s}{r^2}$ , here s is strength of light and r is distance

So $0.74=\frac{s}{{25}^2}$

$s=462.5$

In second case

Intensity is given by $I=\frac{s}{r^2}$

So $I=\frac{462.5}{45^2}=0.2283volt$