We have a long wire with a circular cross section and radius a = 2.40 cm. The current density in this wire is uniform, with a total current of 3.00 A. Find the magnitude of the magnetic field at a distance of 0.72 cm from the center axis. Treat the wire as a cylinder.

The magnitude of the magnetic field is 7.49x10⁻⁶T

Explanation:

The magnetic field is:

Where

i = current = 3 A

R = radius = 2.4 cm = 0.024 m

r = distance = 0.72 cm = 7.2x10⁻³m

Replacing:

the answer is neither ball has a charge.

because if they were both positively charged, they will repel each other.

if they were positively and negatively charged, they will seek.

compass can be used day and night, cloudy or sunny