Convert 15*c in Fahrenheit

Current enters a circuit at a: 1.positive terminal 2.negative terminal 3.low potential side 4.resistor

What is the earliest point in the universe that we can observe? why can’t we see back further than this?

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?