Sound from a loudspeaker has to travel through two materials before it arrives at a microphone. Which pair of materials results in the least time taken for the sound to reach the microphone?
- Amaterial 1: air, material 2: hydrogen
- Bmaterial 1: air, material 2: water
- Cmaterial 1: copper, material 2: aluminium
- Dmaterial 1: water, material 2: oil