Answer:
Directly counting blood cells or tissue cells by using a hemocytometer can determine the concentration of a known volume. Counting the number of colonies that arise on a pour plate can calculate the concentration by multiplying the count by the volume spread on the pour plate.
In radiation, we don't need medium to conduct heat or energy but in conduction we need medium to conduct energy or heat ! conduction is done by contact as in radiation there is no contact !
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