What causes the poles of the electromagnet in an audio speaker to repeatedly switch directions? a metal striker that pulls on the magnet
a diaphragm that vibrates around the magnet
a current that rapidly switches direction
a device that opens and closes a circuit

Which explanation describes the forces involved for a person to walk down the sidewalk? a. the person's feet push backward on the sidewalk; the sidewalk pushes backward on the person. b. the person's feet push forward on the sidewalk; the sidewalk does not push on the person. c. the person's feet push backward on the sidewalk; the sidewalk pushes forward on the person. d. the person's feet push forward on the sidewalk; the sidewalk pushes forward on the person.

Why can blue light and yellow light combine to produce white light? question 17 options: they are both primary colors of light. they absorb each other's wavelengths. because blue, yellow, and white are primary colors. they are complementary colors of light.

Chemical energy is a form of energy. a. heat b. kinetic c. potential d. electromagnetic