What is the name of the perceived change in a sound wave’s frequency due to motion between the observer and the sound source? diffraction
Doppler effect
reflection
resonance

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?

Is a copper wire a conductor or insulator?

Identify the type of heat transfer occurring when chocolate melts in your hand