The electromagnetic force is ?
A. attractive.
B. repulsive.
C. both attractive and repulsive.
D. neither attractive nor repulsive

One day, after pulling down your window shade, you notice that sunlight is passing through a pinhole in the shade and making a small patch of light on the far wall. you see that the patch of light seems to be a circular diffraction pattern. it appears that the central maximum is about 1 cm across and you estimate that the distance from the window shade to the wall is about 3 m. what is (a) the average wavelength of sunlight? (b) the diameter of the pinhole?

The passing of heat through a material while the material itself stays in place. a. radiation b. conduction c. convection

The two required components for a generator are