The magnetic field b at the center of a circular coil of wire carrying a current i (as in fig. 20–9) is:
b = u0*ni/ 2r
where n is the number of loops in the coil and r is its radius. imagine a simple model in which the earth’s magnetic field of about 1g= (1 * 10 ^-4 t) near the poles is produced by a single current loop around the equator. roughly estimate the current this loop would carry.

choosing tennis and golf balls is your inde choice.

their mass and volume are dep

there is no correct list among the choices you've provided.

the list might look something like this:

-- baby human

-- piccolo

-- flute

-- soprano singer

-- trumpet

-- tenor singer

-- trombone

-- baritone singer

-- baritone horn

-- bass singer

-- tuba

since i had to make up the list myself, i made it easy on myself, and i didn't try to shuffle the string instruments and woodwinds into it too.

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2