Question

Your boss asks you to design a room that can be as soundproof as possible and provides you with three samples of material. The only information on each sample's label is the material's coefficient of absorption. The coefficient of absorption listed on Sample A is 30%, on Sample B is 47%, and on Sample C is 62%. When your boss asks for your choice and the reasoning behind it, what would you tell him?
A. Sample C would be best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the smallest.

B. Sample A would be best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the largest.

C. Sample C would be best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the largest.

D. Sample A would be best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the smallest.

Answer 1

The correct answer is A.

The coefficient of absorption of material A is 30%. So, the material will absorb 30% energy of the incident wave falling on it. Thus, the reflected wave will carry the rest 70% energy.

The coefficient of absorption of material B is 47%. So, the material will absorb 47% energy of the incident wave falling on it. Thus, the reflected wave will carry the rest 53% energy.

The coefficient of absorption of material C is 62%. So, the material will absorb 62% energy of the incident wave falling on it. Thus, the reflected wave will carry the rest 28% energy.

Hence, material C would be the best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the smallest.

Answer 2

I believe the answer is A