5. How does amplitude of a wave relate with the energy it carry?
A. The higher the amplitude, the higher the energy.
B. The lower the amplitude, the higher the energy.
C. Amplitude of the wave does not affect its energy.
D. As amplitude of the wave increases, its energy remains the same.

18. If illumination varies inversely to the square of its distance from the light source, which would likely happen if the distance from a light source were increased to twice its original value?
A. The illumination will be doubled.
B. The illumination will be halved.
C. The illumination will be reduced to one-fourth of its original value.
D. The illumination will be increased four times of its original value.