Timmy placed a horseshoe magnet on his desk. he then sprinkled some iron filings around the magnet. in the images below, the poles of the horseshoe magnet are shown in white. which of the following images best shows how the iron filings arranged themselves?

The 3rd image

Explanation:

A magnet has 2 poles, north and south. Magnetic fields originate from the north pole and the move to the south pole.

They are concentrated at the poles where they are strongest.

The best  image that demonstrates the arrangement of the magnetic fields is the 3rd image.

c)as speed changes, wavelength and frequency change.

everything changes!