Do electromagnetic waves travel through a medium

A sound wave has a frequency of 450,000 Hz. What is the wavelength?

How are AC and DC generators different? In AC generators, commutators produce alternating current. In AC generators, no commutators or slip rings are used. In DC generators, slip rings produce direct current.

The principle of conservation of momentum is most similar to which of newton's laws of motion?

A man with mass 82 kg runs at a speed of 2.8 m/s. How much kinetic energy does he have?

How is hydroelectric power created? A. Gas pushing a turbine that generates power B. Water pushing a turbine that generates power C. Wind pushing a turbine that generates power D. Air pushing a turbine that generates power

A geologist estimates that a large boulder weighs 7840 N. What should he estimate the mass of this boulder to be? A. 650 kg B. 740 kg C. 780 kg D. 800 kg

Two objects have the same momentum. Do the velocities of these objects necessarily have (a) the same directions and (b) the same magnitudes? Give your reasoning in each case.

If you keep voltage constant and increase resistance resistance, what happens to current?

A scene in a movie has a stuntman falling through a floor onto a bed in the room below. The plan is to have the actor fall on his back, but a researcher has been hired to investigate the safety of this stunt.

During energy transformation, all energy systems: are a. 100 percent efficient b. lose energy c. gain heat energy d. create energy