When the frequency is high, what happens to the amplitude of the wave?

• A. Low
• B. High
• C. The same
• D. Unknown

Answer: (A)

Frequency tells how often the wave cycles occur each second, while amplitude tells how tall the wave is and relates to the wave’s energy per unit area. These properties are independent. For light, the color of the light depends on frequency, while the brightness depends on amplitude (the energy in the wave). If you keep the same energy input from the source, changing the color (frequency) does not automatically change how tall the wave is, so the amplitude stays the same. Only altering the source’s power would change the amplitude. So the amplitude would remain unchanged when frequency increases, not automatically become lower.