What's the relationship between frequency and efficiency of a machine

Bohr's model could only explain the spectra of which type of atoms? single atoms with one electron single atoms with more than one electron bonded atoms with one electron bonded atoms with more than one electron

Electric charge is what ? a. kinetic energy b. radiation c. discovery d. electricity

Three cards with holes are arranged in a straight line. a light is shined through the first card’s hole and travels through all three cards. what does this tell you about light rays? a) that light is reflected b) that light is refractive c) that light travels in a straight line d) that light does not travel in a straight line