Answer:
In this given statement , the plastic base becomes negatively charged because plastic is an insulator . And the metal cup does not become charged because metal is a conductor.
Explanation:
<u>Reason behind , why plastic base becomes negatively charged -:</u> When a plastic base is rubbed with a dry cloth in the metal trophy, electrons are shifted from one material to the other. Thus, the substance that gains electrons (which is the plastic base) becomes negatively charged. thus , the plastic is an insulator , which causes charge (negative ) by rubbing.
<u>Reason behind , why the metal cup does not become charged -:</u> The metal cup is a conductor, and the surplus charge on the metal flows to the person who charges the cup and to the ground so that it is not charged. Thus, rubbing a metal can trigger hand\finger injury because metals generate excess heat in rubbing .
The natural blind spot is due to lack of receptors where the optic nerve and blood vessels leave the eye. There can also be artificial blind spots when something blocks light from reaching the photoreceptors, or when there is local adaptation of the retina as just after seeing a bright light
