If the amplitude increases by a factor of 3, how does the power change?

If the amplitude increases by a factor of 3, how does the power change?

• A. 9x
• B. 3x
• C. 1/3x
• D. No change

Answer: (A)

Power is proportional to the square of the amplitude. If the amplitude increases by a factor of 3, the power increases by 3^2 = 9. In electrical terms, P is proportional to V^2 (with resistance fixed), and the RMS value scales with the amplitude, so tripling the amplitude makes the power nine times larger. The same idea applies to wave intensity: it scales with amplitude squared. So the power becomes nine times the original. The other options would imply a linear change, a decrease, or no change, which doesn’t fit the squared relationship.

Power is proportional to the square of the amplitude. If the amplitude increases by a factor of 3, the power increases by 3^2 = 9. In electrical terms, P is proportional to V^2 (with resistance fixed), and the RMS value scales with the amplitude, so tripling the amplitude makes the power nine times larger. The same idea applies to wave intensity: it scales with amplitude squared. So the power becomes nine times the original. The other options would imply a linear change, a decrease, or no change, which doesn’t fit the squared relationship.