A cylindrical conductor of length ‘l’ and area of cross section ‘A’ has a resistance ‘R’. Another conductor of length 2.5l and resistance 0.5R of the same material has area of cross section ?

R = (ρ x l)/A [Resistance = resisitivity times length divided by area of cross-section]

0.5R = (ρ x 2.5l)/A'

0.5R/2.5 = (ρ x l)/A'

R/5 = (ρ x l)/A'

R = 5(ρ x l)/A'

(ρ x l)/A = 5(ρ x l)/A'

A' = 1/5 A

A' = 0.2 A

cell differentiation  is how generic embryonic  cells  become specialized  cells. this occurs  through a process called gene expression. gene expression is the specific combination of genes that are turned on or off (expressed or repressed), and this is what dictates how a  cell  functions.

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