To arrive at a microphone, sound from a loudspeaker has to travel through two materials. Which pair of materials would let the sound reach the microphone in the least time?
- Amaterial 1: air; material 2: hydrogen
- Bmaterial 1: air; material 2: water
- Cmaterial 1: copper; material 2: aluminium
- Dmaterial 1: water; material 2: oil