Maglev, a vehicle that glides above a magnetic field without touching a track, make a 624-mile trip in 4 hours. What is the speed of the vehicle? (Type only the number in your answer--no units.)

What color of light must blue light mix with to create white light? a. yellow b. white c. blue d. green

Modern physics a photon emitted from an excited hydrogen atom has an energy of 3.02 electron volts. which electron energy-level transition would produce this photon? a. n=1 to n=6 b. n=2 to n=6 c. n=6 to n=1 d. n=6 to n=2 i chose b but the correct answer is d can someone tell me why? and what's the difference?

What is the most useful equation for electric power?