Which of the following statements is true about magnetic fields. magnets and magnetic fields were only just discovered in the last 500 years. the earth’s magnetic field is confined within the core of the earth. the earth’s magnetic field protects the surface from strong electrical currents coming from the sun. magnetic fields are unreliable for use in navigation.

Afisherman notices that his boat is moving up and down periodically, owing to waves on the surface of the water. it takes a time of 2.70 s for the boat to travel from its highest point to its lowest, a total distance of 0.700 m. the fisherman sees that the wave crests are spaced a horizontal distance of 6.50 m apart. a. how fast are the waves traveling? b. what is the amplitude a of each wave?