the magnetic field at a certain point next to a wire carrying 10.0 A of current is 4.20x10^-5 T. what is the field at that point when the current is 20 A

B=8.40x10^-5 T

Explanation:

To find the magnetic field at the new current, first you need to find the distance. To do so, alter the original equation from finding the field to finding the distance.

r (distance) = 4 pi x 10^-7 / 2 pi multiplied by 10.0 / 4.20 x 10^-5

which equals 0.04762

Next, just plug the numbers back into the original equation, taking into account the requested changes.

which equals 8.40x10^-5

Also it was right on Acellus ;)

Hope this helps :)

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .

this is poiselle's equation from fluid mechanic in physics. mech eng