The intensity on a screen 20 ft from the light will be 0.125-foot candles.
<h3>What is the distance?</h3>
Distance is a numerical representation of the length between two objects or locations.
The intensity I of light varies inversely as the square of the distance D from the source;
I∝(1/D²)
The ratio of the intensity of the two cases;

Hence, the intensity on a screen 20 ft from the light will be 0.125 foot-candles
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It is number 3. Because microwaves are the lowest of the sepectum then visible light the the highest of them all is Gamma Ray's. Hope this helps!!
Answer:
unknow e and f
Explanation:
In experiments with alpha particles that are obtained by the method of radioactive decay of atoms, some parameters are known
a) Known. The initial velocity is given by the energy of the particles entities by the atomic nuclei
b) Known. The particle charge always 2e, helium core
c) Known. It is set in the given experiment, in general it is selected as zero
d) Known. Placed by the experimenter
e) Unknown. The speed depends on the interactions with the system
f) Unknown. It depends on the interactions with the system, because the position depends on the interactions
g) Known. It is always the value of a helium nucleo